A young North Vietnamese government official making his first trip to the south was asked what he thought of this city, formerly named Saigon. His terse reply came without hesitation. "Not well organized," he said.

Some days later the northern cadre had a more elaborate verdict: with their warmer climate and rich agriculture, southerners did not have to work as hard as people in the hard-scrabble north, who were forever struggling against the elements. He found southerners quite friendly, but noted they had an "easier life." They bothered little about building and fixing up their houses, but paid "much attention to food." He stopped short of calling them lazy.

A native southerner, also a government employe, put it more starkly: "They don't like us, and we don't like them," she said. "They the northerners think they know everything, but they are ignorant." She expressed the familiar complaints here that northerners are rigid, dogmatic, domineering, with a tendency to behave like conquerors and, sometimes, like carpetbaggers.

Ten years after Communist forces -- mainly consisting of 15 North Vietnamese infantry divisions -- routed troops of the U.S.-backed South Vietnamese government and captured Saigon, the "reunification" of the country is still sometimes an uneasy partnership.

Like the proverbial shotgun wedding, this marriage of north and south is often marked by mutual mistrust and, at least where the south is concerned, considerable misgivings.

Yet, after 10 years under the same roof and nine years of sharing the same name -- the Socialist Republic of Vietnam, proclaimed upon formal reunification in 1976 -- the two partners seem to be getting used to each other.

"In a sense, things have gotten worse," said a longtime government critic. "It's more restrictive here. But then, we're more used to it now. People adapt."

Indeed, the road to reunification has not been strictly a one-way street. While imposing its vision of "socialist transformation" on the south, Hanoi increasingly has had to contend with a phenomenon dubbed "reverse assimilation," in which influences from the south have affected -- some would say infected -- the north.

According to diplomats in Hanoi, these influences include an awakening of enterprise spirit in the north, more openness to foreign culture and greater availability of western goods, and a somewhat more sophisticated urban lifestyle. The influences can be seen in the spread of consumer goods and western-style clothes in Hanoi and heard in the blare of cassette tapes by American and European rock groups.

The authorities in Hanoi "are very much afraid of this southern influence, because the south is much more dynamic," said a European diplomat in the Vietnamese capital. "If they let things go freely, the south would certainly swallow the north, and this they cannot accept. But they have to accept a certain level of influence from the south into the north, otherwise assimilation won't work."

As a result, according to Vietnamese observers, some of the differences between northerners and southerners are gradually fading. For example, although accents still differ -- sometimes to the point of mutual incomprehension -- it now is much more difficult to tell the difference between northerners and southerners by their appearance, said a former South Vietnamese senator. And some northern women have even been known to visit "institutes of beauty" in Saigon for cosmetic surgery.

How the next generation will behave in the future when leadership inevitably falls to it remains a big question mark. While the young are heavily indoctrinated in the Communist system in schools all over the country, some diplomats detect signs of disaffection among youth in the north as well as the south.

"The youth in the north are more like their counterparts in the south now," one diplomat said. "They want to listen to western music and wear jeans. They don't have the war spirit and war motivation of the older generation."

"I have a feeling the younger generation is starting to have enough of all these sacrifices," said a western ambassador. "The morale of the younger generation is much lower than before. There's a diminishing enthusiasm among young people for the ideals of the party."

In an effort to have assimilation its own way, however, the north appears to have pursued a policy of sending to the south those Vietnamese of southern origin who were "regrouped to the north" around the time of the 1954 Geneva agreement that divided Vietnam at the 17th Parallel.

About 1 million northerners went south at that time to escape Communist rule, and 70,000 to 80,000 southerners went north to join Ho Chi Minh's revolutionaries. The children of these southerners were kept together and educated in special schools in the north, apparently with the purpose of eventually returning to their native provinces, according to several of them interviewed in southern cities.

Hanoi also has been sending peasants from overcrowded northern provinces to "New Economic Zones" in the south. How many have been sent is not known, but one official of a state farm near Saigon disclosed that, in one example, 16,000 people from the Hanoi area are now living in a New Economic Zone near Dalat.

While continuing hostility and insidious influences from the south pose problems for Hanoi, the Communist government can count reunification as a great success in one fundamental asepct: it has encountered no significant armed resistance. 10,000 Still in 'Reeducation' Camps

Although South Vietnam fielded well-equipped armed forces and local units by the end of the war totaling more than 1 million men and including the world's fourth-largest Air Force, the Communist takeover was so complete that no counterrevolutionary threat arose.

Instead, as many as 1 million former government officials, military men and others associated with the Saigon government were sent to "reeducation" centers, according to Hanoi's justice minister, most for a few days or weeks.

"Not more than 10,000" inmates remain in the reeducation camps, Justice Minister Phan Hien said in an interview in Hanoi. But he refused to say how many were "old residents since 1975" -- in other words, detainees associated with the former government -- and how many were "newcomers not worth putting on trial."

Other estimates put the number of reeducation camp inmates upward of 40,000.

In addition, nearly 1 million Vietnamese have fled the country by various means -- mostly by boat -- since 1975, with almost half of them eventually resettling in the United States. The Vietnamese account for the bulk of an Indochinese refugee exodus in the last 10 years totaling about 1.6 million people, including Cambodians and Laotians who have fled the Communist takeovers and continued fighting in their homelands since 1975, according to the U.S. Committee for Refugees.

Mai Chi Tho, the chairman of the People's Committee of Ho Chi Minh City and a senior Communist Party official, blamed this "very unhappy, complicated situation" on American "economic, political and propaganda measures" directed against Vietnam.

"American propaganda made a great fuss about a bloodbath aimed at getting revenge against all those who collaborated with U.S. imperialism," he said this month in a news conference. But Hanoi showed leniency toward those "responsible for the suffering of our people, for slaughter and for war crimes" by merely sending them to reeducation camps, he said.

"After the liberation we did not attempt to take revenge," Mai Chi Tho said. "We did not establish tribunals or secretly execute them, even though some are war criminals and should have been punished like the fascists in Europe" after World War II.

Explaining why these inmates still have not been tried, Justice Minister Phan Hien said, "If we put them on trial, they will risk a death sentence, and we don't want to have a bloodbath."

He also seemed to rule out a deal with Washington to send reeducation camp detainees to the United States, although it was Vietnam that originally proposed the arrangement.

"I believe it is not wise to free somebody if you can foresee that this guy will harm you afterward," Phan Hien said in colloquial English. "We can't release them if once they return to their villages or hometowns they create a danger for people in those places. And if now we send them abroad, we must have the guarantee that those people will not do harm to our interests. It is logical."

He said his response to the argument that demonstrations against the Vietnamese government cannot be prohibited under U.S. law was that "the CIA and the FBI have the means to avoid those regrettable acts."

Phan Hien said some of those released were "recidivists" who "committed crimes against the security of the people" after they were freed.

As an example he cited the case of former prime minister Nguyen Van Loc, who he said was released from a reeducation camp after complaining that he was sick.

"He tried 16 times to go abroad by boat," Phan Hien said, "and on the 16th time he succeeded. Then when he was in Singapore he made a statement against us, and he complained of ill treatment."

Asked why there was so much concern about such statements, the justice minister replied, "The Vietnamese are a people who don't want ingratitude in society. We want people to be truthful and constant."

Phan Hien insisted, however, that the number of "old residents" in the camps was diminishing "month by month."

According to Mai Chi Tho, "30,000 former officers have been released from the camps, including four generals," but he did not mention over what period. He blamed Peking for some prolonged detentions.

"The release of those people would have been much easier if we were not faced with the hostility of the Chinese authorities," he said, without elaborating.

In any case, Mai Chi Tho said, "at present, all our enemies have been wiped out of Vietnam." This has "helped the reunification of our country a lot," he said.

"We don't have any antigovernment guerrillas as in other countries in the area," Mai Chi Tho added. "We have no public demonstrations against the policies of the government. This means our security is pretty good."

Some of the regime's detractors here also think it means that the Communists run a fairly efficient police state.

Certainly, the system of informers and surveillance is so well developed that no antigovernment plots here have been able to get off the ground. Last November, for example, after a show trial in Ho Chi Minh City, 21 persons were convicted of espionage and attempting to overthrow the government with the help of China, Thailand and the United States. But the trial revealed that, although they did appear to be involved in some kind of antigovernment activity, they had not yet committed any actual act of violence.

Three of the men were later executed, two had their death sentences commuted to life imprisonment, and the rest received jail terms. The trial was widely interpreted here as a warning to southerners to toe the Communist line. Montagnards in Highlands Still Fight

Other, less publicized trials have raised questions about the extent of resistance activity. In December, for instance, three men were tried in Song Be Province for allegedly organizing underground military activity within a reeducation camp, diplomats said. They are believed to have been executed, although no announcement has been made, the diplomats said.

So far, the main armed resistance actions in the south have been attributed to Montagnards in the Central Highlands belonging to an organization called the United Front for the Liberation of Oppressed Races, known as FULRO.

In an apparent reference to the group, Hoang Tung, a spokesman for the Communist Party secretariat, said in Hanoi recently that "elements who worked for the former regime in the south, and are now the reserve force of the CIA and China, are actively trying to create internal disorder in our society."

As part of a "U.S. postwar scheme against us in the south," Hoang Tung said, small tribal groups "supplied by China through Thailand" were "operating here and there" to carry out sabotage.

"At night they will attack a village to seize property or kill people," he said. "Sometimes they will ambush a car or a truck, but never a troop position."

According to a well-informed Vietnamese source, local authorities in the town of Ban Me Thuot reported in early March that four Communist cadres had been assassinated in Dac Lac Province since the beginning of the year. He quoted the authorities as saying that about 40 FULRO guerrillas armed with Chinese weapons had been captured or killed in an ambush by Vietnamese troops in February in the province, but that about 10 escaped. He estimated that only about 100 FULRO guerrillas were still fighting and said that now "FULRO doesn't threaten us anymore."

According to the Communist Party newspaper Nhan Dan in an article last month, FULRO "refused to surrender and give their weapons to revolutionary authorities" after South Vietnamese forces capitulated in 1975. It said the period of greatest FULRO activity came in 1976-77 when the organization "thought it could occupy the province Dac Lac and cause insurrection in the entire high plateau."

A western diplomat said he saw half a dozen helicopters laden with rockets take off on a mission heading west from Nha Trang a year ago, leading him to believe guerrillas in the highlands might still be active. However, he never learned the result of the mission.

At this point, said another western diplomat, "I think the kind of resistance that worries the Vietnamese in the south is not FULRO or any armed resistance. It's the passive resistance to socialization and anything coming from the north." One indicator of this resistance, he and other diplomats said, could be an upsurge of interest in religion, particularly among young people and especially Catholics.

In Ho Chi Minh City on Easter Sunday, for example, the cathedral was overflowing with worshipers, including many youths.

"It's very moving to see it," said the archbishop of Saigon, Nguyen Van Binh, in an interview. "I can't explain. They're looking for something. Ordinarily when we are in need, we have recourse to God more easily."

Diplomats estimated the number of Catholics in Vietnam, including the north, at 3.5 million to 5 million. But Archbishop Binh put the figure at 6 million.

He said that about 200 priests were arrested after 1975, but that many had been freed in the last few months. Now, he said, there are about 50 remaining in reeducation camps. Among those still held, Binh said, are Msgr. Nguyen Van Thuan, a nephew of assassinated South Vietnamese president Ngo Dinh Diem detained in the Hanoi area; the Rev. Tran Van Khoa, a missionary in central Vietnam being held in the plateau area, and the Rev. Nguyen Cong Doan, the leader of Vietnam's Jesuit community.

Binh confirmed a Vatican radio report last year that the archbishop of Hue, Nguyen Kim Dien, had been interrogated by authorities for 120 days last year about his opposition to a new, state-created Solidarity Committee of Patriotic Vietnamese Catholics. Dien is said to fear that the committee is aimed at creating a "national church" split from Rome, like the Catholic Church in China. But Binh said he and other bishops -- there are 40 in Vietnam -- were taking a wait-and-see attitude toward the committee.

Binh said Archbishop Dien currently was not in prison or under house arrest, but that he was not free to perform his duties. Many churches remain open, Binh said, but most seminaries except Hanoi's are closed pending a government reorganization to limit their number and impose new restrictions.

Other forms of passive resistance, diplomats said, include refusal to join cooperatives, pay taxes, be drafted into the Army or work for any government entity. 'We Have No Future Here' -

One such resister is Vo, a 45-year-old pedicab driver in Ho Chi Minh City who works only at night to avoid having to join a cooperative and pay taxes. Before 1975, he said, he worked as an accountant for private companies, but now he does only this menial labor because "I refuse to collaborate with the Vietcong."

Vo said he had tried to leave Vietnam by boat three times, spending about $5,000 for the attempts, all of which failed. "I am very unlucky," he said. "Now I have no more money."

His story is not unusual, but his vehemence is.

"I have much bitterness toward the Vietcong," he said, "but I don't have any weapon, and they are very well armed."

While most of the more desperate Vietnamese probably have already left the country since 1975, many like Vo still want to get out. According to the U.S. Embassy in Bangkok, 584,200 Vietnamese are on file as requesting legal resettlement in the United States under the U.N.-sponsored Orderly Departure Program. Many will leave legally if it is possible, and some undoubtedly will continue to risk illegal escapes as "boat people" if it is not.

"We have no future here," said one Orderly Departure applicant whose father was a colonel in the Saigon army.

For their part, the Hanoi authorities seem prepared to accept a certain amount of disgruntlement.

"I think the majority of peasants and handicraft workers are satisfied," said Vice Premier Tran Phuong. "Of course, the number of people who don't like our regime in the south is much bigger than in the north. But as long as they don't take up arms, we leave them alone. and the realities of life will bring them closer to us."