On the surface, the rout of the Senate Democrats last week by Ronald Reagan's budget-cutters looked even more complete and demoralizing than the previous week's massacre in the House of Representatives. But appearances in this case were deceiving.

In the House, the Demorcatic leadership tried to stand firm and held 176 of its 239 members in line behind a Democraic substitute that would have preserved at least the framework of the social programs threatened by Reagan's economies. In the Senate, Democratic leader Robert C. Byrd (D-W.Va.) surrendered to Reagan 10 days before the first show was fired, and 27 of the 45 Senate Democrats followed their leader into Reagan's cost-cutting camp.

That, at least, is how it looked in the headlines. But the real story was more subtle and may even suggest that the Democrats are learning to play the cards they were dealt by the 1980 election a bit more skillfully.

In recent weeks, such smart fellows as Rep. Leon E. Panetta (D-Calif.), columnist Mark Shields and former party chairman Robert S. Strauss have suggested that the beginning of wisdom for the Democrats is the recognition that Republicans now run the government and, as Strauss put it, "the opposition has to pick its spots" for challenging those in control.

The House Democratic leadership did not do that. Believing the normal 57-vote Democratic majority in the House was a real measure of strength -- which events showed to be untrue -- the Democrats fashioned a budget ot thier own and pitted it in a floor showdown against Reagan's. To the mortification of the leadership, 63 Democrats defected on that vote to give Reagan an easy victory.

Equally serious, even though more Democrats (including Rep. Jim Jones of Oklahoma, the architect of the Democratic counter-budget) quaitly slipped over to vote with Reagan on final passage, White House figures' show 72 Democrats from districts carried by Reagan voted against the president on the final test. Those Democrats are hanging out to dry, politically speaking, and if Reagan is anywhere near as popular in 1982 as he is today, they will be prime targets for Republican challenge.

The Senate Democrats played it differently. Facing a nine-vote Republican majority, they made no effort to pull together a budget of their own. Byrd waived any pretense of party discipline, saying before the debate began that, despite his doubts about the "tenuous" assumptions underlying Regan's budget, he would vote for it because "the people want to give him a chance."

Picking up the cur, three-fifths of the Senate Democrats voted the same way. Among those facing the voters in 1982, the split was 13-6 for the Reagan budget (with one absentee), while those whose terms run to 1984 or 1986 divided 14-12 on the issue. As Sen. Wendell Ford of Kentucky, the chairman of the Senate ydemocratic Campaign Committee (who voted with Reagan himself), smoothly explained, "As of now, that fellow down Pennsylvania Avenue has captured the hearts and minds" of the voters.

But the Senate Democrats managed to have it both ways. Before most of them lined up with Reagan, they took advantage of the opportunities provided by eight amendments to send messages of sympathy and support to specific constituencies. None of the amendments passed, but that did not diminish their political utility.

Thus, Sen. Quentin N. Burdick (D-N.D.) voted (unavailingly) to boost veterans' funds and school-lunch money, to prevent reductions in Social Security cost-of-living allowances, and co-sponsored an (unsuccessful) amendment to transfer $200 million from foreign aid to farm programs. In an interview with a Fargo TV station, Burdick echoed Byrd's line that his constituents wanted the president's program to have a chance.

Sen. James R. Sasser (D-Tenn.), facing a reelection challenge from a conservative Republican congressman, was a bit more selective. He cast two votes for the Social Security pensions and one for the farmers, before joining Reagan on final passage and declaring, "I think it is important that President Reagan have an opportunity to demonstrate whether his economic program can work. The budget cuts are not going to be easy but . . . there is no partisan interest where economic issues are concerned."

And Sen. George Mitchell (D-Maine), an appointed senator with two eager Republican representatives on his tail for 1982, backed six of the eight budget amendments, including a modes shift from defense to education and income security, before becoming the only northeastern Democrat to support the Reagan budget.

"I have no difficulty defending my position," Mitchell said, "since I believe the need to control inflation is paramount. But I did so with reservations, manifested by my votes on specific amendments."

Some criticize these tactics as political cowardice -- or, as the British say, being "too clever by half." But in the eyes of Bob Strauss and other Democrats, it is just a way to "live to fight another day."