In the Soviet Union, the title "comrade" (tovarish) was used instead of gendered titles or nobility. It would be used instead of "Mister" or "Sir" or "Misses" or other such titles. For post-Tsarist Russia this was a major innovation — it was an expression of egalitarianism, of the lack of hierarchy. Even Lenin was really just "Comrade Lenin" when addressed formally. When the atomic scientists wrote to thank Stalin for his support on making the bomb, the letter starts with "To Comrade J.V. Stalin — Dear Josef Vissarionovich!" (In practice, of course, there was considerable hierarchy in the USSR — which is part of why the term has been so lampooned.)
Hitler's use of "comrades" is not in this sense — it is a colloquial, "my comrades" sort of sense.
