Nearly a decade and a half after Richard M. Nixon, a distraught former president beset by the past, flew home to California, another former president has followed in his path - serene, popular and proclaiming that he looks to the future as he nears his 78th birthday.

The contrasts between Nixon and Ronald Reagan were inescapable as Reagan flew west after George Bush's inauguration Friday. Reagan left Washington declaring that it was "very pleasant living" in the White House but there are "a lot of things yet to be done" outside of it.Nixon, driven to resignation by the Watergate scandal, took off by helicopter from the South Lawn of the White House on Aug. 9, 1974, and was aboard an Air Force jet to his native state by the time Gerald Ford was sworn in to succeed him.

Reagan, whose own administration was plunged into turmoil by the Iran-Contra affair he professes not yet to understand, sat by benignly on the Capitol's western porch as Bush took the oath of office. Then he boarded a helicopter for the eight-minute flight to Andrews Air Force Base and the same jet trip west.

Nixon, born and raised in California, called his departure from Washington "the nightmare ending of a long dream."

Reagan, a Midwesterner who adopted California as his home, said the journey back there for him and former first lady Nancy Reagan was "a return to a life we did love very much."

Nixon went to an exile of seclusion and silence - first in California, then in New York, then in New Jersey - only recently emerging to proclaim his views in books, articles and public appearances.

Reagan said he will quickly be "out on the mash potato circuit" pushing his proposals for budgetary and electoral reform.

Asked what he would miss most about Washington, he said, "I haven't tried (thinking about) that; it was very pleasant living there . . ."

As to what they would like most about their new life, he said, "Well, because it will be a return to a life we did love very much. California isn't a place in my mind, it's a way of life, so that is the sweet part of the bittersweet experience."

Reagan often conferred with Nixon while in office and once said that as fellow Californians they had a "closer bond" than he enjoyed with former presidents Carter or Ford.

Nevertheless the two men's attitudes toward past and future seem to differ greatly.

Nixon, 61 when he left office, asked diplomat Vernon Walters some months later, "What did I do wrong?"

If there is any such soul searching in Reagan, he does not show it.

The circumstances of his departure as the first president since Dwight Eisenhower to complete two terms are, of course, immeasurably happier.

Still, the stark contrasts stand out. In his farewell to his staff in the East Room, Nixon said, "Always remember, others may hate you - but those who hate you don't win, unless you hate them."

In Reagan's East Room farewell, as in Nixon's, there were tears aplenty. But no talk of hate.

On his helicopter flight to Andrews, Nixon leaned his head back against his seat back and closed his eyes and heard his wife, Pat, murmur, "It's so sad. It's so sad."

Reagan, asked as he jetted back west if he was sad, happy or relieved, replied, "There are elements of all that, yes."

**** Reagan's note to Bush

Inscribed on joke-shop stationery that bore the printed heading: "Don't Let the Turkeys Get You Down," Reagan wrote:

"Dear George. You'll have moments when you want to use this particular stationery. Well, go to it. George, I treasure the memories we share and wish you all the very best. You'll be in my prayers. God Bless you and Barbara. I'll miss our Thursday lunches. Ron."

Showing the note to reporters, Bush said none of those assembled should take the "turkey" reference personally. "It is a broad, ecumenical statement," he grinned.