In passing, Wesley Adamcyzk made the point that unlike the Nazis, the Soviets didn't make a big point of killing children.
I think that comes from their respective notions of The Great Enemies.
The Nazis conceived of their enemies as biological groups which needed to be eliminated. So children - gene carriers - were targeted for murder, too.
The Soviets thought of their enemies as economic groups. They thought re-education at least had a chance of working - particularly with the young.
Their stands on the nature/nurture divide
Led to different sorts of democide.