What the Soviet Union did is more akin to what North Korea is doing now. Death isn't the primary goal, but control; death being either a side effect or a means to that end. Christ, sounds so goddamn clinical, how I put that, but that's about as clear as I can make the nebulous idea floating in my head.
What Nazi Germany did was primarily to exterminate a people, with slave labour used to squeeze some weapons out of them before they died.
Not necessarily. During Stalin's reign there were many ethnic groups who he purposely vetted ruthlessly almost akin to genocide.
Take the Chechens for example, after WW2 he was just like "yeah I don't like Chechens"(to put it simply) and deported hundreds of thousands of them to labour camps to die in Siberia.