House-Senate conferees yesterday resolved all the major differences in the two versions of President Carter's civil service revision bill, virtually ensuring final passage of the historic legislation within the next two weeks.

The civil service reorganization, a major victory for Carter, makes possible sweeping change in the 100-year-old system by which presidents manage their huge federal work force of 2.1 million, excluding postal workers.

Carter has made its passage a top domestic priority, calling it essential to any effort to make government more efficient and responsive.

Two major compromises cleared the way for yesterday's agreement.

On the controversial issue of how much evidence will be required in firings and other actions against federal workers, the conferees leaned toward the Senate version, which mkaes it easier to fire a worker for incompetence than the House version.

The senators deferred to the House side, however, in the area of labor-management relations. They agreed to adopt most of a hard-won compromise contained in the House version, which gives organized labor several of its long-sought goals.

Alan K. Campbell, chairman of the Civil Service Commission, said afterward that the Carter forces were delighted. He said the bill that has emerged from the conference is "better than either the House or Senate version" as far as the administration is concerned.

Campbell said he is particularly happy at the conference committee's decision to approve a full-fledged Senior Executive Service for 9,000 top federal managers, a key part of the president's plan. The conferees decided against several proposals that Campbell said would have limited or weakened the new executive corps.

Among the major elements of the bill are:

Creation of the Senior Executive Service in which top managers will be allowed to trade some of their present job security for higher pay and other rewards for superior performance and risk firing or demotion for poor work. The president and top officials will have greater flexibility in assiging these managers, but the bill includes limits on the percentage of positions that can go to political appointees as opposed to career civil servants.

Pay raises for 72,500 midlevel managers and for supervisors (GS 13 to 15) would no longer be tied to longevity in the job but would depend on performance.

Managers would have greater flexibility in firings, demotions and other personnel actions through what the Carter forces consider a streamlined appeals process. Also for the first time employes fighting such actions would have the right to choose between the statutory civil service appeal route and union arbitration machinery.

Federal employes' unions would have access to an independent federal labor relations authority patterned after the private sector's National Labor Relations Board. Also, the rules that govern federal recognition of unions will be given the force of law, so that they no longer can be revoked by presidential fiat.

The unions also gained a wider scope of bargaining, automatic voluntary dues withholding and most - though not all - other concessions contained in the House version adopted by the conferees yesterday.

The Civil Service Commission would be split into two bodies: the Office of Personnel Management, which would serve the president in the management of his work force, and the Merit System Protections Board, which would protect employes' rights, adjudicate their grievances against management and, along with a new special counsel, protect so-called whistle-blowers against reprisals.

The only major element of Carter's plan that Congress refused him was his proposal to curtail sharply veterans' preference rights in federal hiring and job retention.Both the House and the Senate, under election year pressure from organized veterans groups, stripped the proposal out of their bills by wide margins.

In the most troublesome area of major disagreement in the House-Senate conference - concerning the standards of evidence to be used against employes - the conferees finally settled on a split-level-system for assuring workers their constitutional right to due process in civil service appeals.

In cases of misconduct, such as drinking on the job, an employer will have to present a "preponderance" of evidence [the same as the current standard]. But in cases of incompetence on the job, which officials say is more subtle and difficult to prove, the employer need show only "substantial" proof that an employe is inadequate in any one of several skills considered critical to the job.

Another potentially explosive issue for the conferees was the question of how to deal with so-called mixed cases of civil service appeals, in which charges of discrimination are raised along with charges of misconduct or incompetence.

The uneasy compromise agreed on yesterday is designed to maintain parity between the Equal Employment Opportunity Commission, which has jurisdiction over discrimination cases, and the new Merit System Protections Board, conferees said. A new three-member tribunal is set up to settle conflicts between the two panels.

Joseph L. Rauh, attorney and prominent civil rights activist, called the arrangement a "sell-out" of civil rights that will "wear out these poor people" by making them go through three different boards.

Conferees will meet Tuesday to wrap up some loose ends, but they urged dissenting lobbyists not to bother trying to change any minds over the weekend. They stressed that yesterday's agreements are final.