The Senate approved a $20.4 billion special money bill yesterday to fund President Carter's jobs and economic stimulus program over the next two years. The vote was 63 to 15.

"Nearly one million new jobs will be directly created by the funds appropriated by this bill and a considerable number will result from the multiplier effect," the Appropriations Committee said in its report.

The bill now goes to conference with the House, which has passed a similar measurt carrying $23.3 billion. Most of the extra House money was to help pay for the $50 income tax rebate, which Carter has recently abandoned. The rebate funds will be dropped in conference.

While most of the money in the bill is for the Carter stimulus program, some is for ongoing programs that weren't funded in regular appropriations bills last year. Here are the key provisions:

$4 billion for construction of job-creating local public works projects in fiscal 1977-78, estimated to create about 300,000 jobs, a Carter stimulus request.

$7.9 billion to expand the public service jobs program from 310.000 jobs to 725,000, another major request.

$1.4 billion requested for special new job programs for youth, veterans and persons in need of new skills, and $59 million for community service employment for the elderly.

$925 million for the remainder of this year for the existing "counter-cyclical" revenue-sharing program, which pays out money to states and local governments whenever unemployment tops 6 per cent, as requested by Carter.

$4.99 billion for the regular, ongoing revenue-sharing program for the rest of fiscal 1977.

Sens. Harry F. Byrd (Ind-Va.), Milton R. Young (R-N.D.) and others worried that the bill would spur inflation. Byrd called it "misguided policy . . . virtually every sign indicates inflation is being stimulated."

However, the only major attempt to slash the bill failed. The Senate rejected, 46 to 33, an amendment by Richard S. Schweiker (R-Pa.) to keep public service jobs at 310,000 and cut those funds from $7.9 billion of $4 billion.

Far from cutting the bill, the Senate added $300 million, not sought by the administration but proposed by Gaylord Nelson (D-Wis.) to pay off communities for sewage plant spending from 1966 to 1972, for which the federal government still hasn't reimbursed them. It also added $225 million for drought aid.