Any change in Communist Party leadership in East bloc nations is of interest because it happens so seldom. There are no elections to unseat the old guard. But this week's removal of Janos Kadar, communist leader in Hungary for nearly 32 years, is remarkable on several counts.

First, the party gathering was relatively open, at least by communist standards. A fierce debate raged between hard-line conservatives and young reformers over Kadar's successor.Second, the reformers won. The new premier, 57-year-old Karoly Grosz, is less a party ideologue and more of a pragmatist, something along the lines of the Soviet Union's Mikhail Gorbachev. The Hungarian Politburo was reduced from 13 members to 11 and the young reformers took eight of the positions from the old guard. Gone is the all-powerful, one-man rule of Kadar.

Third, a new party policy statement promised greater public voice in economic and political affairs, what it called, "Socialistic pluralism." It also cited a larger role for private enterprise, and greater autonomy for trade unions.

In fact, the changes were so sweeping that Western observers were caught off guard by what happened.

Much of what came out of the party conference was similar to the policy changes pronounced by Czechoslovakia's Alexander Dubcek in 1968. However, in that instance, however, Warsaw Pact troops stormed in afterwards and imposed iron rule. This time, there will be no invasion because the Soviet Union is encouraging reform.

Hungarians are familiar with Russian soldiers. A courageous uprising in 1956 briefly drove out the Soviets, who returned in overwhelming force and crushed the freedom fighters. Kadar was put in charge.

Kadar was a hated man, but he introduced some mild economic reforms of his own in the 1960s and 1970s that brought relative prosperity to Hungary, at least by East bloc standards. Yet in the 1980s, he blocked further reforms and adopted policies that have sent debt, deficits, and prices soaring. The Hungarian economy suffers from the same rigid communist ideology that has made the Soviet economy a mess.

What happens now bears watching. The transition in Hungary may indicate similar changes among the aging leadership in other East bloc nations. Many of those officials have been in office nearly as long as Kadar. Like Kadar, most took office in the midst of crisis, or upon the death of a previous communist leader.

All of this change is hopeful. It means less ideology and presumably less tension with the West. But it should be kept in mind that for all the proposed reform, Hungary has not suddenly become a democracy.

More private enterprise may make life a little better economically for Hungarians, but they will continue to live in a one-party state. If they ever try to introduce real democracy, the Soviet tanks surely would be back just as quickly as they were in 1956.