The Reagan administration yesterday shrugged off the latest Soviet explanations for the shooting-down of Korean Air Lines Flight 007 Sept. 1, with a White House official calling them "the same old allegations, with no new evidence, delivered by different persons with a different tone of voice."

State Department spokesman Alan Romberg said the Soviets still had provided no evidence for their central contention that the airliner was on a spy mission, nor any evidence that they had tried to identify the plane or force it to land before shooting it down.

Romberg added that the Soviets' refusal to allow U.S. and Japanese craft into Soviet waters to help search for the wreckage "reduces the likelihood" that the airliner's "black box" flight recorder will be found. The black box presumably would answer some remaining questions about the flight, including why it strayed hundreds of miles off course into Soviet airspace.

In the meantime, yesterday's exchanges only added to the questions by accentuating differences between the U.S. and Soviet versions of what happened. The Soviets, for example, said they fired 120 warning shots at the Korean jetliner; the United States says there is no record of any warning shots. The Soviets say the Korean plane and a U.S. reconnaissance plane flew side by side for 10 minutes; the United States says they were never closer than 75 miles to each other.

Some of the major differences in U.S. and Soviet accounts of what happened in the early morning darkness near the Soviet island of Sakhalin:

* Spy plane charge. The Soviets, beginning with the second statement on the incident issued by the Soviet news agency Tass on Friday, Sept. 2, have sought to portray the plane that entered their airspace as on a "pre-planned" intelligence mission.

Yesterday Soviet Marshal Nikolai Ogarkov, in a rare news conference in Moscow, went further than previous Soviet spokesmen, claiming that the Korean jet's route, which took it over sensitive military areas, its actions and its "rendezvous" with an American RC135 reconnaissance plane outside Soviet airspace "led the Soviet control point to the result conclusion that an American airplane was entering Soviet airspace."

Ogarkov charged that in one interval the two planes flew "side by side" for "approximately 10 minutes." He suggested that this was done to confuse Soviet ground radars tracking both planes and that the RC135 was "controlling" the Korean jet on an intelligence mission.

White House officials last week said that there was an interval when the planes were "close to" each other "for a few minutes." But officials also have said that the closest the planes ever came to each other was 75 miles, that they were then going in opposite directions and that by the time the Korean plane was shot down the U.S. jet had landed 1,000 miles away at its base in Alaska.

The United States and Korea have called "preposterous" charges that the 747 jetliner was on a spying mission. The RC135 reportedly had been sent up to monitor activity off the Soviet peninsula of Kamchatka, where Soviet missile tests are held. Such flights are standard monitoring activities allowed by arms-control agreements.

* Warning attempts. The Soviets continue to maintain that they tried "every warning possible" to signal the Korean jet to follow them, including calling the plane by radio on international distress frequencies and firing tracer and machine gun bullets along the plane's path in an effort to force it to land.

There is no evidence in the record of radio reports from the pilot of the Korean plane to the control tower at Narita airport in Japan, however, that he saw anything unusual, such as fighters passing in front of him or tracer bullets. The pilot also apparently did not know he was off course. His last transmission, reported from Tokyo, came just three minutes before the missile struck.

These recordings were reported from Japan, and have not been released here. If the Soviets tried to radio the airliner on international frequencies, that probably would have been heard by Narita, but was not. The United States also maintains that the Soviet fighters do not have radios that can broadcast on those frequencies; the Soviets say they do.

Furthermore, communications by the Soviet fighter pilots with their commanders on the ground monitored by Japanese listening posts show no evidence that the pilots fired warning shots or tracers. The transcripts of those communications released by the Reagan administration cover the crucial 20 minutes or so when the airliner was over or near Sakhalin Island, where it was shot down. Ogarkov's statements yesterday strongly imply that this is when the warning shots were fired.

The plane also had passed over Kamchatka Peninsula. But little information has been made available here on that phase of the Korean airliner's flight, and it cannot be determined if the Soviets tried to warn the plane there.

Ogarkov suggested there were attempts to radio the plane at that point. U.S. officials have said privately, however, that Soviet fighters did not come close to the airliner over Kamchatka and instead apparently flew in the direction of the RC135 off the coast.

* Weather. President Reagan said it was "a clear night with a half moon." U.S. officials said there was cloud cover at 6,000 feet, well below the airliner and fighters, which were all between 30,000 and 35,000 feet at the time. A Tass statement Sept. 6 claimed "conditions of bad visibility" at the "height of night," and Ogarkov yesterday described it as a dark, cloudy night.

* Identification. The sharpest and most revealing differences are over whether the Soviet pilots knew what they were shooting at. U.S. officials have said that the Korean plane, when it first strayed over Kamchatka Peninsula, "was initially identified by the Soviets as an RC135 and then as an unidentified aircraft."

But U.S. officials say they believe it is virtually impossible for the Soviet fighter pilots to have mistaken the unique size and shape of the 747, even at night, and not to have known they had their sights on a commercial airliner.

In transcripts made available here the Soviet pilots talk about seeing lights on "the target" aircraft, which would contradict the assertion by Ogarkov and other officials that the plane was traveling without lights. The 747 was also equipped with a strobe light unique to civilian airliners.

But there has been no indication that the Soviet pilots ever got close enough to read the Korean Air Line name or symbol or identified it as anything but "the target."

This factor has led many Americans to accuse the Soviets of either extreme brutality in knowingly shooting down an airliner or extreme incompetence in failing to make a thorough identification and report it to ground commanders.

The Soviets, however, essentially claimed yesterday that it didn't matter because they were convinced that whatever plane it was that entered their airspace was on a spy mission.

"We did not have any doubt about the airplane, whether a military or commercial airplane . . . . We were looking on it as an espionage reconnaissance aircraft . . . ," said Leonid Zamyatin, the chief information specialist on the Communist Party's Central Committee.

Ogarkov alluded to the possibility of a mistake in identification, however, even though he gave no indication that Moscow would have acted differently.

"It's easy to sit here and compare the silhouette of one airplane with another," he said, saying that the 747 silhouette is "similar" to that of other aircraft. But at night, he said, it is difficult to compare differences, "so it's quite possible that the silhouette of one plane could be mistaken for the silhouette of another."

American pilots say the stock in trade of interceptor pilots is supposed to be expertise in identification.

* Official statements. The Soviets did not officially admit shooting down the plane until Sept. 5, five days after the event. The initial Tass statement Sept. 1 acknowledged only that an unidentified plane had entered Soviet airspace, that fighters had been sent aloft to warn it and that the plane "continued its flight in the direction of the Sea of Japan." The Soviets did not say that flight continued after a missile had been fired that started the plane on its spin toward the ocean.

The United States, roughly 12 hours after the plane went down, announced Sept. 1 in some detail that the Soviets had shot the plane out of the skies. On Sept. 3, The Washington Post reported that some analysts suspected that the Soviets may have misidentified the Korean jet as an RC135, which is a much smaller four-engine jet. At the time, it was not known that an RC135 was actually in the air.

On Sept. 5, after a briefing for congressional leaders, the White House announced that an RC135 had been in the vicinity of the Korean jet at one point in international airspace and on Sept. 6 reported that the Soviets had initially misidentified the Korean jet as an RC135.