In terms of total power? Maybe.. Hitler was not the ultimate Dictator like he seem to many today, but in terms of genocide? Not really. Even if the famine in the Ukraine, you are probably referring to, was a planned event and not just missmanagement and ignorance, it still would be no organized genocide to wipe out a whole race.

Why do you abbreviate USSR that way? The first I assumed was a typo, the second makes it look intentional.

I do not see how that tracks from either the English translation, the original Russian name for the country: "Сою́з Сове́тских Социалисти́ческих Респу́блик", or the transliteration: "Soyúz Sovétskikh Sotsialistícheskikh Respúblik".