Secretary of State Cyrus Vance and Soviet Foreign Minister Andrei Gromyko left here today with sharply different public assessments of what had been achieved in three days of intense negotiations between the two nuclear superpowers over new arms limitation agreements.

Both top-ranking diplomats asserted that "some progress" had been made in efforts to lay the groundwork for a new accord, but Vance departed with a generally positive statement that the talks had been both "useful and constructive," while Gromyko voiced a decidedly negative view.

The negotiations that ended Friday night undisputedly revived the bargaining process between Washington and Moscow that had been stalemated for more than a year.

That achievement alone, Vance said at a press conference, improves the "atmosphere" of Soviet-American relations that had been growing increasingly sour. He acknowledged, however, the "serious differences remain between us" on the terms of a new strategic arms limitation pact.

Gromyko, in remarks at the airport, went further in declaring that positions are still in conflict on fundamental points.

"One cannot draw the conclusion," he said, "that there is already progress on the road to a solution of the main problems.

"From what I can gather, the United States has not given up its attempts to undermine the security of the Soviet Union. We cannot accept that kind of agreement."

Gromyko also said, however, that "there has been some progress on a certain number of questions." Compared with the flat rejection that the Carter administration received when Vance brought two American proposals to Moscow in March, Gromyko's comment reflects at least some new willingness to bargain.

A joint communique issued here today reflected that attitude of compromise.

As a result of the talks, the communique said, "the differences between the two sides on several of the previously unresolved questions have been narrowed. Discussions . . . will be continued with the aim of an early conclusion of a new agreement."

It was clear from Vance's press conference and the language of the communique - even before Gromyko's airport remarks - that the terms of an actual accord still need to be worked out, and Vance acknowledged that "that will be difficult."

Vance, for example, claimed at his news conference that "we have reached general agreement on a common framework for the SALT II agreement.=

What this means, in the U.S. view, is that the structure and format for a new pact has been achieved, although there is still no agreement on the actual content of the accord - specifically how many and what kind of nuclear weapons will be limited.

The communique, however, did not report agreement on such a framework. It stated only that "progress had been made in developing a common framework for further negotiations."

Yet, the firmness of Gromyko's airport comments seems to show that the Soviets take a more pessimistic view and that after the acrimony of recent months, reaching a SALT pact will not be so easy. It is alos possible that after the toughness of their position in March, the Soviets do not wish to be seen as shifting directions too quickly. Moscow's anger over Carter administration policy on many issues has become a major theme of Kremlin pronouncements.

One subject upon which there seemed to be general agreement between the two sides was the need to resumee the Middle East peace conference.

The communique said that Washington and Moscow will "direct their joint efforts toward resuming the work" of the long-dormant Geneva Middle East conference, of which the two countries are cochairmen.

The participants said reconvening the conference, hopefully by the fall, could be an important factor in negotiating a settlement to the Arab-Israeli confrontation. The Geneva conference has not met since its opening session in late 1973 and the United States and Soviet Uniln now have agreed to have regularly monthly consultations in an effort to get the conference reopened.

On SALT, Vance repeatedly declined to reveal to reporters any details of how the large number of serious and controversial specific issues - such as new U.S. cruise missile, Soviet Backfire bomber, or modernization of existing nuclear-tipped missile forces - might be handled.

He said it would be useful to discuss such details now.

According to Vance, there are three basic elements to the new framework agreement that would succeed the existing U.S.-Soviet interim pact signed in 1972. That pact expires Oct. 1.

A portocol that would run for three years from the time the basic treaty is signed. While Vance did not explain the purpose of the protocol, it presumably would be a means of dealing with two controversial issues that have arisen since Vladivostok - the U.S. cruise missile and the Soviet Backfire bomber.

A statement of general principles that would govern the conditions of a third SALT agreement in later years.

Vance said he wanted to "make the point very strongly" that all three parts of this potential agreement framework were "interdependent," one upon the other.

What this means is that if a second SALT agreement is actually reached in the coming monahs, it is most likely to be a compromise that is closer to the Soviet position that to the plan most favored by the Carter administration for much larger cutbacks in numbers of weapons than the Soviets are now willing to accept.

Thus, the United States has been stressing, as Vance did today, that any new agreement must contain a commitment to continue the SALT process toward the broader goals.

It was primarily the Carter administration's determination to go beyond the terms of the Vladivostok understandings of Noverber 1974 - which put a ceiling of 2,400 on the number of strategic missiles and bombers - to more radical cutbacks that angered the Soviets during the March talks. The administration has now apparently accepted that so sweeping an agreement is impossible for the time being.

The basic Soviet stance is that a new accord should include restraints on the U.S. jet-powered cruise missile, a crucial new area of weapons technology in which the United States has far out-stripped the Soviets. The United States is not prepared to accept those restrictions unless they are combined with similar limitations on advanced Soviet armaments, such as mobile missiles and missiles that destroy enemy missile silos.

These differences, among others, are the one Vance and Gromyko suggested must still be resolved.

Vance said there was dispute over "whether certain items should go in the treaty or the protocol, whether some items should be included at all in both these documents and the precise nature of all items to be included Wash.), whose objections in large

A successful three-tiered accord, he maintained, would represent a "blending" of the U.S. proposals and Soviet propositions. While the process fo blending has begun, Vance would not venture a guess whether it could be completed this year.

Should a bargain be struck, it would still have to be acceptable to powerful congressional and Pentagon figures such as Sen. Henry M. Jackson (D-Wash.), whose objections in large measure brought about the failure to achieve ratification of the Vladivostok understanding reached by President Fort and Soviet party leader Leonid Brezhnev.

Vance said that he expected to meet with Gromyko again before long but no date was set.