IN THE GREAT political laboratory of Eastern Europe, all six of the former Soviet-bloc countries have now held elections. In Czechoslovakia, which along with Bulgaria voted over the weekend, large decisions near. In the six months since it threw off Communist rule, it has been under a transitional government whose chief responsibility was to prepare these elections. Lacking the authority that only a free vote can confer, the government deferred many of the harsh and demanding choices that lie ahead. These months have been a time of rejoicing to the point of euphoria, and the country is firmly committed to transforming its economy. Now it has to decide how to begin.

The great winners in Czechoslovakia are its remarkable president, Vaclav Havel, his Civic Forum and its Slovak counterpart Public Against Violence. They represent a sort of visionary anti-politics -- a mistrust not only of the Communist Party but of all parties. Their idealism has some appeal, but it's going to take a much more muscular style of organization to bring the country through the tests that now await it. Czechoslovakia's standard of living is higher than most in Eastern Europe, and its people are less gripped by a sense of crisis. That has allowed Czechoslovaks to delay decisions into which their neighbors have already plunged. But further delay would be costly.

Bulgaria, in contrast, has evidently voted to march into the new world under the same party that has governed it since World War II. It's been renamed the Socialist Party, and there have been some changes at the top, but it's the incumbent government that has won. The reasons are fairly clear. The opposition was badly disorganized. Communism has allied itself with Bulgarian nationalists against the Turks in a land where ethnic and national enmities are undiminished. Above all, Bulgaria is a country isolated from Western Europe's prosperity and its democratic culture.

Of the Soviet-bloc countries that were under Communist governments a year ago, the northern four have now turned decisively to democratic leadership. To the south, things are less clear. Yugoslavia has not yet held free elections at the federal level, although non-Communists have recently won in two of the republics. In Romania the voters last month chose a government that is, in effect, the Communist opposition to the late dictator Nicolae Ceausescu. Now Bulgaria has also chosen to stay with the old party and trust it to improve its habits. The former Communist countries of Central Europe are moving vigorously in one direction, while those of the Balkans seem to be going, with less certainty, in another.