Israeli Prime Minister Menahem Begin tonight delivered a lengthy and emotional public lecture to Secretary of State Cyrus Vance on dealing with the Palestine Liberation Organization and declared that Israel will never accept the PLO as a partner in peace talks.

Comparing the PLO to the leadership of Hitler'se Germany and calling its national covenant an Arabic "Mein Kampf," Begin said bitterly that there may be some people who learned from mistakes in history how to repeat them. He obliquely compared the United States to those who told Jews in Germany not to pay too much attention to Hitler's declarations.

(Carter administration officials in Washington had no comment last night on the Begin remarks, treating them as a episode, rather than a decisive development in the negotiations.)

The remarks, a reiteration of Israeli policy on the PLO, were significant in that they came amid reports that tha Palestinians are softening their longstanding opposition to recognition of Israel and because they came as Vance and Begin began crucial talks on how to move toward a negotiated settlement of the 30-year-old Middle East crisis.

Earlier today, Israeli Foreign Minister Moshe Dayan told reporters that in some respects Israel did not see "eye to eye" with the United States. But, he added, Israel was prepared "to take care of ourselves."

Begin chose a formal toast at a state dinner, with Vance sitting at his side, for his rebuff to U.S. signals to the PLO and declarations that the United States will immediately start discussions with the organization if it recognizes the existence of Israel.

Vance, who finished his first round of talks with the Israeli leader several hours earlier, peered expressionless over the top of his half glasses as Begin spoke. Reading his previously prepared reponse, Vance made no referened to the PLO issue. He appealed to Israel to take bold actions in pursuit of peace despite the uncertainty and risks involved, saying that the alternative is continuing comfrontation and war of an even more destructive nature than in the past.

In his toast, Begin read parts from the PLO charter and said, "That organization, the philosophy of which is based on an Arabic 'Mein Kampf,' is no partner whatsoever and never will be a partner to hold any talks."

In similar terms, Dayan said earlier that even if the PLO accepts U.N. Security Council Resolution 242, which recognizes Israel's right to exist and calls for a negotiated Middle East settlement, "it will not mean that we accept the PLO as a partner for negotiations for peace."

President Carter said yesterday that a PLO acceptance of Resolution 242 "would open an avenue" for PLO participation at a Geneva conference on the Middle East.

Today's public statements pointed up one of several serious differences betweent the American and Israeli positions.

U.S. officials said Vance did most of the talking in today's sessions with Begin. Dayan and other Israeli officials, explaining U.S. ideas. Arab reactions and Vance's assessment of the status of the U.S. drive for a comprehensive peace agreement.

According ot the American side, Begin responded only briefly and mostly about issues that had arisen, which appeared to be a reference to the PLO question.

Israeli officials, however, said most of today's talks revolved round the PLO and that Begin expressed his views in terms similar to those he used at tonight's state dinner.

Dayan, in a press conference, refused to discuss what he had heard in the talks with Vance but restated the Israeli negotiating position without substantial change.

"I don't think the acceptance, if there will be an acciptance, without any reservations by the PLO of ("Resolution) 242 means automatically abolition of the (PLO) charter."