Lenin was smarter than Stalin. Stalin was more brutal than Lenin, if that was possible. However, I think that Russia would have been different by some degree if Lenin has kept Stalin from power. The same for the way the Soviet Bloc would have been formed.
Also, Lenin would have to deal with Trotskyite. Stalin did, by killing him.
All theoretical constructs. What is, is.
This conjecture provides yet another avenue of rationalization for the socialist left: ‘If Lenin hadn’t been poisoned by Bush - er I mean Stalin - communism would have worked and the world would be a workers paradise’. Or something like that.