President Reagan concluded his voyage of personal diplomacy to Geneva last night declaring that he had "moved arms control forward" at the summit and telling a joint session of Congress that he had tried to convince Soviet leader Mikhail Gorbachev that missile defenses could help the superpowers "escape the prison of mutual terror."

The president's nationally televised address capped a wearying 20-hour day that took Reagan from a final appearance with Gorbachev in Geneva to a session with allied leaders in Brussels and then home to Washington, where he reported directly to Capitol Hill and was received with sustained applause.

Reagan acknowledged in his report that the United States and the Soviet Union remain "far apart" on many issues. He said Gorbachev, in a "very direct exchange of views," had rejected his appeal for "my dream" of missile defenses, "which could ultimately protect all nations against the danger of nuclear war."

The president offered a generally optimistic view of the prospects for better relations with the Soviets, but also cautioned that his two days of long, private talks with Gorbachev had not brought the superpowers closer on fundamental issues or resolved specific differences on arms control.

He expressed hope of ending the tensions and mistrust that characterized his first term and suggested that his second would be different, seeking to resolve differences by candid and direct talks with Gorbachev, who might lead the Soviet Union into the next century.

Appearing vigorous at the end of his long day, Reagan, who puts great store in the value of personal relationships with other leaders, emphasized the personal contact he had with Gorbachev. "That was the best part, our fireside summit," he said in a reference to sitting beside fireplaces in the frigid setting of Geneva for more than five hours of one-on-one discussions.

After reporting on their agreement to meet twice in the next two years, once in the United States and once in the Soviet Union, Reagan joked that "we arranged that out in the parking lot."

"We met, as we had to meet. I had called for a fresh start -- and we made that start. I can't claim we had a meeting of the minds on such fundamentals as ideology or national purpose -- but we understand each other better. That's key to peace. I gained a better perspective, I feel he did, too," Reagan told Congress.

Reagan, in a dramatic flourish, flew by Marine helicopter from Andrews Air Force Base to the Capitol to deliver his address, following an eight-hour, 4,000-mile flight from snowy Brussels, where he had reported to the allied leaders on his talks with Gorbachev. It was a gesture identical to one used by President Richard M. Nixon when he flew to the Capitol to report on the signing of the first Strategic Arms Limitation Treaty in Moscow in 1972. "Maybe it's the old broadcaster in me," Reagan said, "but I decided to file my own report directly to you."

The central part of Reagan's report was on his disagreement with Gorbachev on the Strategic Defense Initiative (SDI), a research program for a proposed space-based shield against nuclear missiles. The Soviets have made SDI their chief target. Reagan used one of his longest private meetings with Gorbachev to explain his commitment to the missile defense system, but the president said last night he ran into deep skepticism from the Soviet leader.

"This discussion produced a very direct exchange of views," Reagan said. "Mr. Gorbachev insisted that we might use a strategic defense system to put offensive weapons into space and establish nuclear superiority.

"I made it clear that SDI has nothing to do with offensive weapons; that, instead, we are investigating nonnuclear defensive systems that would only threaten offensive missiles, not people," he added. "If our research succeeds, it will bring much closer the safer, more stable world we seek. Nations could defend themselves against missile attack, and mankind, at long last, escape the prison of mutual terror -- this is my dream."

The president also said he had described to Gorbachev his idea of "open laboratories" to "permit Soviet experts to see first-hand that SDI does not involve offensive weapons" and to allow Americans to get a look at Soviet research programs on strategic defense that Reagan said have been going on for "many years."

Reagan told Congress he "reassured" Gorbachev that if the U.S. research demonstrates "a defense against nuclear missiles is possible," the United States would offer to share it with allies and Moscow in an attempt to "replace all strategic missiles with such a defense, which threatens no one."

Reagan said he told Gorbachev "that we are a nation that defends, rather than attacks, that our alliances are defensive, not offensive. We don't seek nuclear superiority. We do not seek a first strike advantage over the Soviet Union. Indeed, one of my fundamental arms control objectives is to get rid of first strike weapons altogether."

The president said he wanted to "give a push" to negotiations in Geneva on nuclear and space weapons, and that both leaders will instruct the bargainers to "hasten their vital work." However, White House officials said the negotiations will not resume earlier than scheduled in January, and Reagan offered no specifics about how the negotiations will be accelerated, as he and Gorbachev promised to do.

"We moved arms control forward from where we were last January, when the Soviets returned to the table," he said. Reagan stressed that he and Gorbachev had called for "early progress" on reducing nuclear weapons by 50 percent, although they still differ on which weapons should be cut, and that they wanted to "turn the talks toward our chief goal, offensive reductions." Such a shift in emphasis could be an indication that both nations are ready to sidestep the deadlock over Reagan's strategic defense program and seek agreements reducing strategic and intermediate-range missiles.

Reagan, who has devoted his political career to criticism of communism, said last night that there will be "enduring competition" between the superpowers, but he called for an end to the tension of recent years. "With all that divides us, we cannot afford to let confusion complicate things further," he said. "We must be clear with each other and direct. We must pay each other the tribute of candor.

"Just as we must avoid illusions on our side, so we must dispel them on the Soviet side," he said. "I have made it clear to Mr. Gorbachev that we must reduce the mistrust and suspicions between us if we are to do such things as reduce arms, and this will take deeds, not words alone. I believe he is in agreement.

"A new realism spawned the summit, the summit itself was a good start, and now our byword must be, steady as we go," Reagan said.

Reagan rejected earlier opportunities to meet with Gorbachev's predecessors, three of whom died in office since 1980, but he returned from Geneva proclaiming the value of periodic summits, saying that continued meetings "can help bridge those differences" that have persisted over 10 previous summit meetings since World War II.

"Where do we go from here?" he asked. "Well, our desire for improved relations is strong. We're ready and eager for step-by-step progress. We know that peace is not just the absence of war.

"We don't want a phony peace or a frail peace," he added. "We did not go in pursuit of some kind of illusory detente. We can't be satisfied with cosmetic improvements that won't stand the test of time. We want real peace."

Reagan said he found Gorbachev to be an "energetic defender of Soviet policy. He was an eloquent speaker, and a good listener."

Reagan devoted only one paragraph of his address last night to each of two major areas of disagreement with the Soviets -- regional conflicts and human rights. He said he told the Soviet leader that the United States will continue to support insurgencies battling "regimes which obviously do not represent the will or the approval of the people. I tried to be very clear where our sympathies lie; I believe I succeeded," he said