I think the difference between Lenin and Stalin was that for Lenin dictatorship was a means to an end in trying to establish the Communist utopia, he didn’t want Stalin to take over from him because he was aware of Stalin’s flaws. Stalin didn’t seem to be so ideologically driven, always seemed more about power for the sake of power and self preservation. But, we should also remember that Lenin was only leader for 6 years or so, and it’s not unusual for a dictator to slowly lose the plot as their power, isolation and paranoia grows we are seeing with the current occupant of the Kremlin so who know how Lenin would have turned out had he been around longer, nor was he a saint in his time in power.