THE BUDGET QUARREL has long since ceased to concern amounts of money. The central question now is which hands hold the final power over government spending. That, as the people who wrote the Constitution were aware, is a fundamental issue of American politics.

If it were only amounts of money that were in dispute, the continuing resolution could have been passed and signed over the weekend without the rigamarole yesterday of pretending to shut down the federal government. The difference between President Reagan's demand and Congress' legislation was about $2 billion--one half of 1 percent of the amount contained in the resolution. In the usual split-the-difference negotiation, the rough edges would have quickly been smoothed.

But Mr. Reagan is in no position for easy compromises. He evidently feels, and with reason, that his economic program will fatally lose momentum if he does not continue, visibly and dramatically, to pursue and capture more budget cuts. The budget-cutting crusade slowed sharply in September because of the internal dissension within the administration. Mr. Reagan has renounced his hopes of a balanced budget in 1984; as the economy slides deeper into recession, a realistic guess at this fiscal year's deficit would be at least twice the last official estimate of $43 billion. The president feels, apparently, that he does not have room to step back that next highly symbolic $2 billion.

It's in the nature of Congress, in contrast, to be less concerned with the budget's grand total than with its separate pieces. In the congressional view, generally speaking, Mr. Reagan is engaging in an unreasonable and oppressive campaign to reopen disputes already argued through and laboriously closed, and to jeopardize commitments that Congress believes it has made to the country. The White House suggests that, if Congress doesn't want to make any more decisions, it can give Mr. Reagan blanket authority to shave off a little more. Most of Congress replies, correctly, that the very idea is an infringement of the constitutional balance of powers.

In political terms, it's worth noting that Mr. Reagan's most formidable opposition is not among the Democrats in the House, but among the Republicans in the Senate. Earlier this fall some of the senators began to take their distance from Mr. Reagan on this second round of budget cuts, and that was the point at which the bills began to run into trouble. It is a political triangle with, increasingly, the Republican Senate making the interesting choices. Because the Senate over the weekend worked out a settlement with the House rather than with the president, a more or less unified Congress collided with him--resulting in the veto.

Both sides have now announced a cease-fire for three weeks. Then, amidst the pressures of the end of the session, and the inducements of the holidays, they will try again to settle their differences before, a month later, Mr. Reagan's budget proposals for 1983 arrive. The artificial crisis of the past several days has sharpened all of the issues, and resolved none of them.