Sen. Abraham Ribicoff was telling Leningrad Communist party leader Grigori Roman that some Democrats in the U.S. Senate might vote against a new strategic arms treaty with the Russians even if their own party chief President Carter, favored it.

"But can't you discipline them?" Romanov asked in astonishment, Ribicoff recalled.

The Connecticut Democrat, co-leader of a 12-member Senate delegation that departed here for Eastern Europe yesterday after a week of touring and talking with Soviet leaders, used the anecdote to help describe what might be called a "comprehension gap" that yawns between this authoritarian government's leaders and those who help make foreign policy in Washington.

The clash of perceptions occurred repeatedly in the seven-day tour, which took the senators to Minsk and Leningrad as well as into the Kremlin for discussions with Soviet President Leonid Brezhnev. Premier Alexei Kosygin and other members of the ruling Politburo. The senators, four Republicans and eight Democrats, found themselves perplexed, sometimes angered, but ulitmately, it seems, fascinated by the differences.

Wherever they went, they said, the senators tried to impress upon their Soviet hosts that the Senate of the United States is an independent branch of the American government, comprising people who may frequently vote along party lines but who jealously guard and revere their right to 100 different points of view - and don't mind speakig them.

The Americans seemed unsure that the Soviets grasped this essential difference.

"They just don't understand the Senate," commented John Glenn (D-Ohio). "We respond back to people in our state, we have our individual responsibilities, where here things float downhill, they get their directions from the top down and that's a whole different concept."

The Senators clearly had their toughest - and angriest - moments during a meeting Thursday with Kosygin, the resilient 74-year old premier.

There, they raised a host of concerns, from human rights to Soviet African expansionism and its anti-Israeli Middle East policies, to conventional arms transfers and the delivery of Mig 23s to Cuba, pressing the point that these issues could adversely affect Senate ratification of a new SALT treaty the Soviet say they very much want.

"I though you came to talk peace. These things are not important," Ribicoff recalled a furious" Kosygain as saying. His refusal to talk about these issues and insistence that the United States is to blame for rocky relations between the two capitals in turn dismay and angered the Americans.

"It's like my sister-in-law," quipped John Durkin (D-N.H.). "What's hers is hers and what's mine is negotiable."

"It was momentary aberration by one man." Ribicoff said during an interview in his suite at the Sovietskaya Hotel. "I don't hold it against a country because one man blew it. SALT is too big an is too big an issue to let Kosygin spoil it."

Ribicoff, using familiar senatorial debating techniques, added with a wearied expression: "I don't get mad at Kosygin, but I do get disappointed. A leader of a great state doesn't have the luxury of getting mad the way he did."

Sen. Henry Bellmon (R-Okla), delegation coleader, said he was "amazed at how closed these people's minds are. It seems that everything they do in the world is for peace, stability, purity, and that we shouldn't even suspect their motives or challenge them."

For their own part, the senators encountered some of the principal puzzling facets of Russia in the 62nd year of Soviet power. Deeply moved by visits to gravesites and memorials in a nation that lost 20 million in World War II, they also were put off by the bellicose attitudes of Kosygin and some others. Although charmed by the warmth of Russian hospitality in the privileged homes where members of the Supreme Soviet entertained them privately for dinner, they also were appalled and outraged after meeting with a group of jews who have been refused permission to emigrate on state security grounds, in some cases for up to 10 years.

"This is far more complex than I realized when I came," said Richard Schweiker (R-Pa.).

Ribicoff commented, "It's tough to understand why any of them are refused. They don't represent any menace or danger to the Soviets. It is a deep tragedy, one of those factors that goes into people's appraisal of the Soviet Union."

He said the senators were told by Foreign Minister Andrei Gromyko that a list of about 200 who have been refused permission to leave will be reviewed "consistent with Soviet law."

Several of the Americans who are knowledgeable on strategic weapons when Brezhnev told them last night the U.S.S.R. had once tested a neutron-enhanced rediation warhead years ago and decided against producing it.