WHEN Israeli Prime Minister Yitzhak Rabin and Palestine Liberation Organization Chairman Yasser Arafat met at the White House two years ago, their reluctant handshake symbolized a grudging conclusion reached by both: that their differences could only be settled through compromise.
When they met again at the White House yesterday to sign an agreement inaugurating phase 2 of the Mideast peace process, their handshake symbolized something more concrete.
''Oslo I was mostly psychological,'' says Robert Satloff, executive director of the Washington Institute for Near East Policy, referring to the September 1993 White House signing ceremony that launched the the peace process. ''This agreement is not psychological but territorial. It is about bringing Arafat to the gates of Jerusalem.''
''If Yitzhak was hesitant to shake Arafat's hand in 1993 it was because of whose hand he was shaking,'' adds Mr. Satloff. ''This time any reluctance was because of the complexity of the deal.''
The 460-page agreement signed yesterday extends interim Palestinian self-rule beyond the Gaza Strip and Jericho to include portions of the West Bank.
Israel will soon begin withdrawing its forces from six West Bank cities plus most of Hebron and from more than 400 West Bank villages. Within about six months, elections will be held for an 82-member Palestinian Council, which will serve as a legislature and executive representing West Bank and Gaza Palestinians.
More-difficult issues relating to the final status of the territories - whether they will eventually make up a fully sovereign Palestinian state, for example - will be addressed in final status talks due to begin next May.
Paradoxically, the two men brought together by yesterday's peace agreement made their careers fighting each other: Arafat as head of an organization dedicated to Israel's destruction; Rabin as the defender of Israel and conqueror of the West Bank and Gaza, mostly Palestinian regions occupied by Israel since 1967.
But despite the history of antagonism between them, the two leaders took similar roads to yesterday's White House ceremony.
After years of defeat and humiliation in his running war with Israel, Arafat reluctantly concluded that compromise and peace were the only way to secure a Palestinian homeland. In 1988 he abandoned his dream of wiping Israel off the map and agreed that Palestine was big enough for two states, one Jewish and one Arab. Months later he formally recognized the Jewish state, meeting Israel's precondition for eventual peace talks.
As for Rabin, the architect of the harsh measures used to crush the Palestinian uprising in the West Bank and Gaza, which started in 1987, was also one of the most receptive students of the lessons it had to teach.
The uprising reinforced Rabin's opposition to the ideal of a ''Greater Israel,'' including all of Palestine, underscored the high cost of holding on to the West Bank and Gaza, and thus reinforced the logic of gradually disgorging the two territories.
Having reached similar conclusions, the two old adversaries have linked their fates, staking their careers on a process dedicated to ending four decades of conflict through compromise.
''The peace process is essential to the future of both men,'' notes one Clinton administration official. ''It's not only that they need each other for their own political futures. They need each other to get things that each one wants for his own people.''
''Yitzhak and Arafat have no great love for each other,'' adds Robert Lieber, a professor of government at Georgetown University. ''But history has locked them into an embrace and a degree of mutual dependence.''
The strongest selling point for Arafat is that the agreement hints at eventual statehood, providing at least limited self-rule in the meantime.
''The fact that for the first time in the modern history of the Palestinians more than one-third of the West Bank ... is going to come under Palestinian authority will be a relief to those who have lived under occupation,'' says Khalil Jahshan, executive director of the National Association of Arab Americans.
The strongest selling point for Rabin is that the agreement advances the peace process while leaving Israel in control of most of the land, water, and security of the West Bank.
''There's clearly an implication of statehood at the end of the process but in the meantime the Israelis are not jeopardizing their security,'' notes Professor Lieber.
It is a fact which accounts for a peculiar asymmetry in Israeli and Palestinian public opinion, as the administration official explains. ''Israelis are reasonably satisfied with the short term but worried about what happens down the road'' he says. The Palestinian public is optimistic about the longer term but less hopeful about what the near term will bring'' in terms of jobs, freedom of movement, and genuine self-rule.
President Clinton began a full-day devoted to the Middle East yesterday by meeting separately with Yitzhak and Arafat, who were later joined by Egyptian president Hosni Mubarak and King Hussein of Jordan.
Predictably absent yesterday was President Hafez al-Assad of Syria, who is negotiating peace with Israel on a separate track.