Secretary of State Cyrus Vance said here today that there are still differences between the United States and Israel over the terms for resuming the Geneva peace talks, despite Israeli acceptance of a unified Arab delegation that could include some Palestinians.

Talking with reporters shortly after his arrival here for two weeks of bilateral meetings with other foreign ministers attending the U.N. General Assembly, Vance said he was "pleased" by Israel's support for the concept of a unified Arab delegation at Geneva. He made it clear, however, that the United States believes Israel has not gone far enough to help resolve, the continuing procedural stalemate.

Some of the conditions set by the Israel cabinet yesterday "do not accurately reflect our views" Vance said.

Vance said he shared the Israeli view that "there should be bilateral discussions" at Geneva between the Israeli delegation and the individual Arab nations represented within a pan-Arab delegation, "but as to the other conditions, there are differences between us."

The Israelis had stipulated that no known members of the Palestine Liberation Organization could participate in the Geneva talks, and that after the opening ceremonies all negotiations would take place between the Israelis and the individual Arab states - Syria, Egypt and Jordan.

Under the umbrella of a unified Arab delegation, Vance said, there could be a number of parties discussing the Palestine aspect of a Middle East settlement. If the Palestinians are there, Vance said, they would be involved in the Palestine aspect of the talks.

Vance also differed with the Israeli conditions by noting that the United States has not ruled out the presence of some PLO members at Geneva.

Vance said that these conditions were "not discussed with the united States before Israel announced them.

Egyptian Foreign Minister Ismail Fahmi, speaking to reporters in a corridor outside the General Assembly chamber after he met with the British, Belgian and Dutch foreign ministers, warned that any proposal for a unified Arab delegation without the PLO "will be a non-starter."

"There will be no Geneva without the PLO," Fahmi said. He charged that Israel "wanted to give the false impression that there was an American proposal with which it sees eye-to-eye, which is not true." As a result, the Egyptian official said, yesterday's Israeli announcement "has no real meaning."

He praised the united States for "making a tremendous effort" to get the Geneva talks going, and said that Vance "is still looking for a formula."

The secretary of state pursued the American initiative last night at a working dinner with Israeli Foreign Minister Moshe Dayan in Vance's suite at the U.S. Plaza Hotel, across the street from U.N. headquarters.

Washington Post Staff writer Dusko Doder reported from Washington that "didn't accept the package as we offered it. But they accepted the basic idea and added their conditions to it. The bottom line, however, is that Israel's move is a small but very important concession."

The immediate Arab reaction to the Israeli move was described by U.S. officials in Washington as "guarded at this point, nothing to suggest rejection."

News services reported that Cairo Radio said the Egyptian government was "studying" the Israeli position but that Egypt would not make a formal response on the issue before Fahmi's return in early October.

A Syrian spokesman in Damascus was quoted as saying Israel's move was aimed at disrupting the Geneva conference, but he stopped short of rejecting the move. Jordanian press accounts suggested qualified approval.

In Israel, former Prime Minister Yitzhak Rabin termed the Israeli acceptance a "wrong decision" because it. "Tackles procedures rather than substance." Rabin said the U.S. proposal "Deals with the public relations aspect of the Arab-Israeli conflict rather than with its substance."

Vance's other meetings at the U.N. touched only peripherally on the Arab-Israeli dispute.

He saw the foreign ministers of Canada. Indonesia and Iran before his dinner with Dayan. His schedule Tuesday includes meetings, with representatives of Finland, Belgium, Portugal, Turkey, Britain, Mexico, Venezuela, Peru, the Netherlands and Guatemala.

Vance will return to Washington on Wednesday to sit in on talks between President Carter and the foreign ministers of Syria and Jordan.

Meanwhile, in the Assembly, the annual general foreign policy debate opened today with a warning from Candaian External Affairs Minister Donald Jamieson that if U.N. bodies continue to engage in what he called sterile debates with predetermined conclusions, "the important decisions affecting the fate of mankind will be made elsewhere and this organization and most of its agencies will winter into insignificance, and eventually unlamented oblivion."

The sentiments, similar to those expressed two years ago by U.S. Ambassador Daniel Patrick Moynihan, were more jarring today, coming from a country that has long been one of the prime supporters of the United Nations.

"Our intention was of try to shake up the organization." Jamieson said afterwards, "and make members aware of the growing irrelevance of many U.N. activities."

One test of the reality of Jamieson's warning is expected later this week in the Security Council, where the United States and Britain will seek to sustain the momentum of their Rhodesia initiative by winning U.N. appointment of a special representative who will join in negotiations for a cease-fire between the white minority government and black guerrilla groups.

The African "front-line states" promised their support of limited U.N. action, according to Zambian officials. It remains to be seen whether the Soviet Union will oppose the Anglo-American plan in the Security Council.