In closing arguments in his six-week trial on perjury charges, former White House aide Michael K. Deaver was portrayed yesterday as either so honorable he had no need to lie, or so afraid questions about his lobbying would harm his influential friends that he lied to protect them.

Those were the sharply contrasting images of the longtime confidant to President Reagan that were given to the U.S. District Court jury that will decide whether Deaver committed perjury in his testimony to a congressional subcommittee and a federal grand jury. The jury is expected to begin deliberating this morning.

"Don't you kid yourself, this a major case," said prosecutor Whitney North Seymour Jr. as he ended a day of arguments to the jury. "It is important to you and and it is important to the community."

Deaver, the deputy chief of staff in the Reagan White House until he formed his own lobbying firm in the spring of 1985, was accused by Seymour of lying "to protect to his friends -- at the top of the list President and Mrs. Reagan . . . .

"If they -- and if the world -- knew how he had used his relationships with them to entice his clients, it probably would have broken their hearts," Seymour told the jury.

Some of the jurors were seen nodding in agreement as Seymour, who practiced his argument in the empty courtroom until 11 Wednesday night, stated the prosecution's case, snapping his fingers to signal for internal government memos to be flashed on a huge courtroom screen.

Herbert J. Miller Jr., Deaver's chief lawyer, was a contrast in both style and manner, delivering a folksy and often rambling defense. Calling himself "that old fellow Miller," he pleaded with the jury to adopt "a common sense" approach that he said would lead them to throw out the case.

"It just doesn't make sense," Miller said, that someone as visible as Deaver would deliberately lie when he knew he was being investigated by the press and five or six government agencies.

Miller also rejected arguments by Seymour that Deaver had traded on his friendship with the Reagans. "Here's the man who could have gone to the president, but because he's the type of man he is, he never did," Miller said.

Deaver, who suddenly rested his case Monday without presenting any evidence, is not "the evil, greedy" man Seymour had pictured, Miller said.

"I tell you, ladies and gentlemen, he is a fine man," Miller said as he crossed his arms and sat on the edge of the desk in front of Deaver. "He is not a cheat. He is not a liar. He is a honorable man."

Seymour, one of a number of independent counsels appointed to investigate corruption in the administration, spoke longer and was more animated in his comments than Miller. "Why? Why?" he asked softly at the conclusion of his nearly three hour-long summation. "Why would a man in Mr. Deaver's position with all he had going for him go before the House committee and a grand jury and give false testimony?"

The answer, he said, was to protect his friends, to save his lobbying clients and hopefully keep alive a contract to sell the firm to a British corporation for about $16 million.

Neither Seymour nor Miller disputed that Deaver, an aide to Reagan for more than 20 years, was once one of the most influential men in Washington. The prosecutor, who spoke first, sought to turn that to his advantage, arguing that despite his power the jury should "treat this defendant as you would treat every man and woman on this earth."

If they did, then the words etched on the Supreme Court building, "Equal Justice Under Law," would have a renewed meaning for the jurors, he said. "Maybe someday when you go by there, perhaps with a grandchild, and you can look up at the words and say, 'I helped those words come alive when I served on the Michael Deaver trial.' "

Miller charged that the case was a product of Seymour and his vain effort to find Deaver guilty of violating the lobbying restrictions contained in the Ethics in Government Act. Having failed at that, Miller said, Seymour searched through the 1,100 answers that Deaver gave to a grand jury and a House subcommittee in 1986 and devised the five-count perjury indictment.

"Anybody who would stand up and yell out at the secretary of state because he said something nice about Mr. Deaver would love to indict Mr. Deaver for violations of the Ethics in Government Act," Miller said, recalling the confrontation between Seymour and Secretary of State George P. Shultz during the trial.

In his rebuttal, Seymour explained why he didn't indict Deaver for ethics law violations. "He blocked the investigation" by lying, the prosecutor said. "We still don't know if there was any violation of the Ethics in Government Act."

Deaver is accused of failing to recall lobbying efforts he made for the South Korean government, Trans World Airlines, Boeing Co., Rockwell International Inc., Puerto Rico, and Canada, contacts that Seymour said were so memorable that no one could forget them.

Seymour recalled that Deaver was paid $475,000 by South Korea and had as one of his primary tasks getting a trade envoy from Seoul into the Oval Office to deliver a letter from President Chun Doo Hwan to President Reagan.

"It really boggles the mind that he could forget that," Seymour said. Deaver had told a congressional panel that he did nothing to facilitate the delivery of the letter.

"Talk about facilitating the letter," the proseuctor said. "He invented the letter," suggesting the idea to Korean officials during a visit to the country.

Miller argued that Deaver could be forgiven his failure to recall many of the meetings and contacts because he moved for years in the high-pressure world of Washington's powerful and had probably had 10,000 meetings while at the White House. "That's what makes the difference between you and me and Michael Deaver," he told the jury. "He met the secretary of state many times. If I met the secretary of state, I would remember it to my dying day."

If convicted on all five counts, Deaver faces a possible prison sentence of 25 years and a fine of $34,000.