What was the de facto difference between countries like Belarus and Georgia, which were within the political borders of the Soviet Union, and countries like Poland or Czechoslovakia, which were not?

Countries within the Soviet Union were considered as Soviet Republic, they were subordinate directly to the government in Moscow. In practice it was just an administrative division with only symbolic independence. What is more important they were all ruled by branches of one party - The Communist Party of the Soviet Union, it's significant because the party have all the power not the government. Communist countries outside the Soviet Union were de facto satellite state of USSR. They were ruled by separate communist parties, by they all were strictly controled by Moscow to the late 80.