I have read quite a lot about it and my conclusion is what I wrote above. A mostly ideological distinction without real difference - even less difference than your examples of theft (intellectual property aside - that is not theft by any definition, but infringement).

People have always tried to conquer other territories, make use of them and settle them. To make an artificial slice out of this continuous and omnipresent phenomenon and call it by another name is incoherent, but then ideologies are mostly incoherent, and colonialism as a very specific sin was a very good and efficient argument in Cold War propaganda and its struggle for influence in the Third World.

Soviets excelled in propaganda, and many of their ideas (like AIDS being an artificial disease, unilateral nuclear disarmament, or the fake contrast between colonialism and membership in the Socialist Bloc) survived the fall of the country.

That said, a very similar line was already pushed by the Japanese in order to paint their own brutal empire as some kind of Pan-Asian utopia. But their trace in global discourse is negligible to the Soviet one, which was much more sophisticated and long-lasting.