"Drawing a moral equivalence in this way is a logical fallacy."
Weeeell...!!!
Here you have two political leaders with a contempt for democracy and prepared to bypass that democracy to obtain objectives, the basic different being that Thatcher was shackled with existing (nods toward) democracy, while Russia was still a melting pot with an great objective - one was seeking to bring changes to a politically primitive country, while the other was fighting to keep things as they were by over-riding hard won rights.
I believe it is possible to compare them, but only by putting them in their individual contexts.
Stalin was a complex character - a failed seminary who served as a minor minister in the early Bolshevik Government and, somewhat unaccountably, was placed at the head of the Soviet Union at Lenin's death, when it was apparent that there were others far more qualified than him to hold the job.
There are several conspiracy theories regarding Lenin's death and Stalin's appointment - little wonder!
It's a little facile to just write off Stalin as a despotic monster - the period is a fascinating one and well worthy of examination and plenty of literature to draw on.
Jim Carroll