Vienna — In late October 25 years ago the Hungarians toppled their totalitarian Stalinist regime. But, shortly after, 2,500 died in vain in a desperate defense of their new freedoms against Soviet intervention.
Today, Hungary is a communist state and a firm member of the Soviet alliance, but it has achieved many of the major reforms for which the ''freedom fighters'' fell.
Neither the popular Hungarian uprising of 1956 nor the more immediate problems of Poland cast any long shadows in Budapest or other parts of Hungary these autumn days.
It is 25 years since that popular uprising and a reform movement aiming at a pluralist, democratic society were put down by the Russians, leaving 10 million bewildered Hungarians facing an uncertain future.
If today the uncertainty has largely gone and if Poland is having less impact in Hungary than in East Germany, Czechoslovakia, and Romania, it is because changes made since 1956 have brought at least some of the democracy the reformers had sought.
Virtually the Hungarians' only concern about Poland is that, if developments finally prompt Soviet intervention, it will mean a tightening up throughout the bloc, and thus a brake on their own reform process.
For a decade they have been accustomed to steadily rising living standards - and to the least repressive, most tolerant and tolerable communist-controlled society in the bloc.
Moreover, they have seen their country become the most stable in the bloc both politically and economically. It has none of the consumer hardships that sparked Poland's crisis and are unsettling Romania, and none of the deep dissent troubling Czechoslovakia.
Instead, Hungary is taking its economic pragmatism and ''market'' reforms a stage further, opening doors to private enterprise and increasing ties with advanced industrial countries that might well mean half its trade will be with the West before long.
East Germany probably has the bloc's highest living standard today, Czechoslovakia is next. Both governments are seeing to it that shops are even better stocked than usual.
But in Hungary not only is the food there - sausage and salami and many other items the Poles can only dream of - but also there is a good atmosphere. ''Marketing is fun,'' a Western woman familiar with Warsaw markets' empty stalls and frustrated queues remarked after visiting Budapest.
Hungary's leader, Janos Kadar, took over in 1956 with credentials that were dubious at best. He served in the government of the ill-fated Imre Nagy, disappeared in a lull in the fighting with the Russians, and returned with them as party chief when the rebellion was finally snuffed out.
Within a short time, however, he launched his famous appeal for national conciliation under the slogan, ''Who is not against us, is with us.'' He has steadily enlarged on it, and no small factor in its success has been his own modest personality and life style and a ''common touch'' that appeals to most Hungarians.
It is one of postwar Eastern Europe's most significant developments that the Hungarians have ''got by'' with reforms quite sweeping by any standard without unduly alarming the Russians.
They have done so largely through a cautious foreign policy that hews strictly to the Kremlin's and sedulously avoids upsetting it on sensitive issues of Soviet ''leadership'' the way first the Czech reformers did and, these days, the radicals in Poland do.
In 1968, for example, Mr. Kadar personally supported Alexander Dubcek to the very last moment. The Hungarian leader reluctantly went along with intervention but kept well in the background for some time till feelings had lowered.
In August 1980, Budapest's restrained reactions reflected strong sympathy with the Poles. The tone changed only some months ago, as militancy in Poland was threatening to get out of hand. But Hungarian spokesmen adopted the bloc's critical line on Solidarity apparently more in sorrow than in anger.
Realism in foreign policy has enabled the Hungarians to hold steadily to their course of domestic reform. Theirs is still the first and only reform in Eastern Europe to receive explicit Soviet approval, openly expressed by Leonid Brezhnev himself at the Soviet party congress in February.
Further bold modernization lies ahead despite anxieties about a lag in industrial growth and about adverse world trade conditions. It will bring:
* New supports for collective farmers, whose tiny household plots are a vital element in Hungarian agriculture, which not only feeds the whole country but also exports to hard-currency Western countries.
* Openings for small-scale private initiative on a large scale, from letting out parts of unnecessary state enterprises or for cooperatives in businesses, light manufacturing, or local services.
* Less government interference in major economic units and still more independence and market judgment for management.
There is a lesson in all this for the Poles, whose prime minister and party leader, Wojciech Jaruzelski, has echoed Mr. Kadar's ''who is not against us . . .'' appeal.
Poles have not rallied to that plea. They remain distrustful of the olish leadership.
Mr. Kadar faced the same problem after the bloody trauma of 1956. Overcoming distrust has been the key to success in Hungary - as it may prove to be for Poland.