A sharp dispute between the Carter administration and Israel over differing interpretations of Prime Minister Menachem Begin's pledge to freeze Jewish settlements in the West Bank territory is blocking the exchange of letters needed to seal the Egyptian-Israeli bargain struck at the Camp David summit, informed sources reported yesterday.

The behind-the-scenes conflict with Israel in Washington and public criticism of the two formal Camp David "framework" agreements from two crucial Arab countries, Jordan and Saudi Arabia, produced a series of moves by the Carter administration to defend its hard-won summit results.

Secretary of State Cyrus R. Vance left the United States for Jordan and Saudi Arabia last night after adding Syria as a stop on his mission of defusing Arab criticism of Egyptian President Anwar Sadat's decision to commit himself to signing a separate peace treaty with Israel by Dec. 17.

The apparently coordinated Jordanian and Saudi decisions to put some distance between themselves and Sadat jolted some U.S. Middle East experts, who fear that Sadat will maintain that Carter is now obligated to "put on the line" the close ties the United States has with both countries in order to get support for the accords.

Other, higher ranking, U.S. officials said, however, that they saw no special cause for concern in the statements, and stressed that both countries were still prepared to receive Vance.

At the same time, the administration was reportedly conveying concern to Israeli officials over the impact that pointed remarks Begin has been making in public since the secretive 13-day summit ended could have on Sadat's ability to sell the agreement at home and elsewhere in the Arab world.

Begin told Israeli television Monday that the phrase "legitimate rights of the Palestinian people" - a phrase written into the accords and crucial to Sadat's ability to win Arab acceptance of the agreement - "has no meaning." He had accepted it to please Sadat and Carter. "and because it does not change reality. We accepted, and everyone has his own interpretation."

The sharpest U.S. concern centers on Begin's repeated assertions that he has agreed to suspend civilian settlements on the West Bank territory of the Jordan River only for a period of about three months. U.S. officials have indicated their interpretation is that the agreement would limit new settlements for five years.

The dispute over these two sharply differing interpretations, which were not resolved in meetings yesterday between U.S. and Israeli officials, is holding up an exchange of letters among the U.S.. Egyptian and Israeli delegations on the settlements and four other topics, informed sources said.

The exchange of letters, which among other points cover settlements, a U.S. commitment to build two military air bases in Israel for the Israelis, and the status of Jerusalem, is last formal act of the 13-day secret summit, which ended Sunday with the signing of two "framework" agreements by Carter, Begin and Sadat.

After hearing briefings from Begin and Sadat on Capitol Hill yesterday morning, some senators and representatives came out surprised at what one senator called "the big gaps in the approaches" of the two leaders to the agreements. Rep. Edward J. Derwinski (R-I11.), told reporters after heafing the two men separately that the Camp David agreement "is far less encompassing than we originally thought."

Begin went from Capitol Hill to the White Houser where he said goodbye to Carter. The Israeli leader will spend today and tomorrow in New York before leaving for home.

Sadat spend 25 minutes with Carter in a farewell meeting. The Egyptian leader flies to Morocco today to meet King Hassan II, and is due back in Cairo tomorrow. Sadat told congressional leaders he will probably be in touch there with Jordan's King Hussein, whose participation he sees as vital to the complex set of negotiations the Camp David accords are supposed to inaugurate.

Hussein seemed to dash any immediate hopes for support that Sadat may have had by authorizing a government statement in Amman yesterday that said Jordan, although refered to in the documents, "is not legally or morally bound" to join the talks or endorse the Camp David results.

Jordan ruled the West Bank, including the Arab section of Jerusalem, until 1967, when Israel conquered the West Bank, Gaza, Syria's Golan Heights and Egypt's Sinai peninsula in the Six-Day War. Under the peace treaty that Sadat has now promised to sign with Israel by Dec. 17, Egypt gets back all of the Sinai, although parts of it will be demilitarized and placed under United Nations peacekeeping forces.

A Jordanian spokesman said Hussein had called Saudi Arabia's Crown Price Fahd to discuss the summit before the issuing of the two statements.

Vance, who left Andrews Air Force Base shortly after sundown last night, added a stop in Syria to his five-day trip to meet with President Hafez Assad, one of Sadat's sharpest critics. U.S. and Syrian officials said the visit is part of the pattern of contacts established between Washington and Damascus five years ago, and that neither expects a significant change of views as a result of Vance's five-hour stopover after he has visited Amman and Riyadh.

As Vance left, U.S. and Israeli officials continued efforts to resolve the potentially dangerous conflict over Israeli settlement rights on the West Bank during the five-year period of "full autonomy" that is to be given to a local Palestinian goverment while negotiations go on about the "final status" of the West Bank and Gaza.

A senior U.S. official told reporters Sunday night shortly before the signing ceremony that Begin had entered into an agreement that would bring a moratorium on civilian settlements for the five-years period. But in subsequent interviews on U.S. and Israeli television, Begin adamantly insisted that he had not made such a commitment. Instead, he said, he had agreed to suspend West Bank settlements for the estimated three months it would take to set up a self-governing authority for the West Bank.

Powell disclosed yesterday that at Israel's insistence a section on the issue of settlements on the West Bank had been lifted out of th framework agreement. A common understanding between the three leaders was to be handled instead in the "side letters" that were due to exchanged yesterday.

But the exchange was put off for at least 24 hours when Israel proposed a text that reportedly did not cover the key second provision of the understanding, as defined by the United States and Egypt.

The United States had understood Begin to agree at Camp David not only to the three-month freeze but also to an arrangement that leaves the issue of future Israeli settlements on the West Bank to be discussed and mutually agreed upon by the four parties involved in the five-year process of deciding the territory's final status - Israel, Egypt, Jordan and the self-governing authority of local Palestinians.

The effect of that arrangement would be to give the three Arab negotiating delegations a veto right over new Israeli settlements.