The rhetoric from Capitol Hill has Democrats and Republicans on opposite sides of guns-versus-butter, the Democrats defending social programs as the Republicans tilt toward defense.

But the Democrats haven't been voting quite the way they talk.

"Almost everyone in the House has said that a lot can be cut out of the defense budget," mused Rep. Patricia Schroeder (D-Colo.), moments after the House easily passed the largest military authorization bill in history Thursday night. "But it's funny--they don't vote that way."

Only a year ago, Congress swallowed almost the entire program of the president--tax and domestic spending cuts, a big defense buildup--in a few large gulps. But this year, Democrats and moderate Republicans said, it would be different. At least in the Democratic House there would be new ideas, new alternatives.

Instead:

* The House last week approved a $175.3 billion defense authorization bill--almost everything the president had asked for--by a vote of 290 to 73. Item after supposedly controversial item in the Pentagon budget--MX missile, B1 bomber, C5 cargo plane, Trident II missile, Pershing missile, civil defense--survived amendment during seven days of debate.

* Meanwhile, in the name of compliance with the budget resolution adopted earlier this year, House committees were also busily voting sizable cuts in domestic spending programs--Medicare, Medicaid, food stamps. They did not always cut as much as their counterpart committees in the Republican Senate had earlier, nor quite as much as the budget resolution called for, and the Democrats made much of these distinctions. But their cuts were still deep.

Late Thursday evening, on defense, House Democratic whip Thomas S. Foley (Wash.) sat rather glumly in a back row of the House. He was whipping no one.

The voting board that dominates one wall of the chamber was lighting up with yeas and nays, as liberals tried in a last--and successful--gesture of defiance to cut the defense bill by just 1 percent. Foley, third-ranking Democrat in the House, was waiting until almost everyone else had voted before casting his own vote, which was in favor.

"I don't want to make either side mad," he explained, referring to the Democrats from the Armed Services Committee and elsewhere supporting the president, and to their liberal adversaries. "There's no leadership position on this."

The tone had been set by House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) the week before. Two days in a row, O'Neill, while going out of his way to excoriate the president's economic program, told reporters he had not had time to decide what position he would take on an amendment cutting funds for the MX, a weapons system that has generated such controversy that the Republican Senate slashed its funding in May.

Reagan's remarkable success this second year in a row on defense was attributable to a number of factors. Many Democrats have always voted for defense; many now believe as the president does that defense was squeezed in the 1970s and must be increased. Some Democrats also fear being labeled soft on the Soviets, or want to cash in on defense-related campaign contributions, or see defense as pork.

"People are looking for fund-raising sources, and the election is only 95 days away," said Rep. Edward J. Markey (D-Mass.), who led the effort to cut back the civil defense program. "Every one of these weapons systems has a constituency. If you want to make the arms contractors happy, you can do so without any peril."

Indeed, liberals and conservatives both fought passionately for innocuous-sounding amendments to help particular contractors in their districts.

Les Aspin (D-Wis.), who has a reputation as an iconoclast on the Armed Services Committee, steered clear of most liberal efforts to slash the budget. And the committee accepted, on voice vote with no debate, an Aspin amendment to require that all major components of tankers leased by the Navy be American-made.

"That's a get-Les-Aspin-reelected-in-Beloit amendment," Aspin grinned afterward, adding that, without it, a firm in his district would have to compete against the Japanese for an engine contract.

Another successful amendment which had members muttering about "carrying coals to Newcastle" would force the Defense Department to use U.S. coal at American bases in coal-rich West Germany. It was sponsored by Republican Paul Trible, who is running for the Senate in coal-producing Virginia.

Meanwhile, Democrat Robert Garcia, who represents the impoverished South Bronx of New York, showed up to propose and lose an amendment to stop Defense Department veterinarians from giving free shots to officers' pets.

The division among the Democrats was clear on the floor. Shoulder to shoulder in the center of the House all week sat the pro-defense senior Democrats of the Armed Services Committee: Melvin Price of Illinois, Samuel S. Stratton of New York, Charles E. Bennett of Florida, Richard C. White of Texas.

With them were the chamber's Republicans, marshaled in part by the White House. Opposing them was a small band led by Armed Services members Schroeder and Ronald V. Dellums (D-Calif.); "the Pat and Ron show," Dellums called their effort at one point.

They were joined intermittently by other liberals--New York Democrat Thomas J. Downey, who led an assault on the Trident II, New York Republican Bill Green, who led a half-hearted incursion on MX research funds. But mostly the chamber was empty, and the liberal Democrats and moderate Republicans who rail against the defense budget back home were nowhere to be seen.

"I've never felt so lonely as I felt in this debate," said Dellums, who sponsored a comprehensive alternative deleting $55 billion in weapons. "Hey, if there's a peace movement out there and millions of Americans are afraid of nuclear war, I didn't sense it on the floor of this Congress."

Ironically, except for the last-minute 1 percent cut, the only arms battle the president lost was the deletion of $54 million for nerve gas weapons, when the debate was led by conservative Republican Ed Bethune of Arkansas. Reagan also came within three votes of losing the battle to cut $1.14 billion in MX procurement, after sponsors invoked the name of Texas Republican John G. Tower, who had cut the funds in the Senate Armed Services Committee.

Dellums' substitute bill lost by a whopping 348 to 55; his amendment to strike funds for the Pershing II missile lost by 311 to 49; his effort to kill the B1 bomber lost 257 to 142. Schroeder's amendment to cut overseas troops in half lost 314 to 87.

"It's typical of defense bills in recent years that they tend to pass virtually unchanged," Foley said.

"Many members say they want controls on the growth of military spending. But when it comes to MX, B1s, chemical warfare or additional tanks, they are unable to make discriminating choices. They are concerned about appearing 'weak on defense.'