There was definitely wealth inequality within the Soviet Union. The Central Asian republics and the Caucasus in particular were notoriously worse off than the rest of the country, while the Baltics (even then) were comparably wealthier. And on a smaller level, Moscow was a lot better off than somewhere out in the Urals or Siberia like Sverdlovsk or Novosibirsk, just due to the proximity of leadership and concentration of wealth and important figures.

It was because of this wealth inequality that the Central Asian republics were quite unwilling initially to secede from the USSR in 1991 and preferred to preserve the union: they were able to receive handouts from the central authorities in Moscow rather than have to deal with things themselves. Conversely, Azerbaijan by the 1980s was quite unhappy with the arraignment, as all the oil money extracted out of the Caspian was not kept locally but instead sent to Moscow, with very little sent back in return.