What type of government did soviet union have?

A dictatorship
 because Joseph Stalin (1878-1953) was the dictator of the Union of Soviet Socialist Republics (USSR) from 1929 to 1953. Under Stalin, the Soviet Union was transformed from a peasant society into an industrial and military superpower. However, he ruled by terror, and millions of his own citizens died during his brutal reign.

The answer is society was a caste like system with poor whites at the bottom of the white social ladder.