Leaders of Rhodesia's black nationalist guerrilla forces presented peace proposals yesterday that are in sharp disagreement with the Rhodesia settlement proposals advocated by the United States and Britain.

Although there were indications that the search for a compromise solution to the Rhodesia problem would continue to be a long, drawn-out affair, British Foreign Secretary David Owen and U.S. Ambassador to the U.N. Andrew Young seemed relatively contented by the results of the first serious bargaining session with Patriotic Front co-leaders Robert Mugabe and Joshua Nkomo.

Meanwhile in Rhodesia, Bishop Abel Muzorewa, one of the three nationalists who have been negotiating with Prime Minister Ian Smith, announced that he was ready to return to the Salisbury talks today. He walked out of them last week after saying he had beer, "insulted" by one of Smith's aides.

Emerging from six hours of the talks here, Owen described the discussions as "very detailed" and said that both sides now had a "much greater depth" of understanding of each other's proposals as well as the objections to them.

"The whole question is the balance of power in the transition period and the need to insure that all the parties to the election have a fair chance, that we have a really genuinely fair election," he remarked.

The British-American proposal called for Smith to surrender power to Britain, the former colonial authority, and for the British to then arrange for election of a black majority government while a U.N. force supervises a cease-fire in the guerrilla war.

Owen hinted that the conference would probably break up today to give time for both sides to reflect on the situation and to search for a mutually acceptable compromise.

British and American negotiators here were heartened by what Stoney Cook, Young's assistant, called "the vibes of flexibility" emanating from Front representatives and the fact that they were finally discussing the terms of the five-month-old British-Amercian plan in such great detail.

Hamilton Whyte, the official Foreign Office spokesman, told reporters, "It all added up to some extremely serious discussion. There are indeed some very considerable differences still between the parties on the two sides of the table."

But, he added, "I think that there is still an attempt being made to feel a way around some of these differences."

Young himself described the talks as "more a seminar than a bargaining session."

A conference, being held in the Grand Hotel Verdala with a commanding view of the isle from the Arab-built walled town of Rabat, is the first time Front leaders and British and American negotiators have sat down together to discuss the pros and cons of the Western peace plan for Rhodesia.