Stalin began participating in Communist party conferences as a young man and was a true believer in Marxism, however there is plenty of historical evidence that he was also a narcissist who wanted to be viewed as a strong and powerful man. The most obviously evidence is his own invention of his surname "Stalin" which translates to Man of Steel or Iron Man; his birth name was Ioseb Besarionis dzе Jughashvili.
His desire to be a "strong" and decisive leader and a good Communist is what led to his disastrous 5 year plan of turning Russia into the breadbasket of the world, which only led to the great famine of 1932-1933. His response was essentially a big shrug. To him, a million deaths was but a statistic (as he is infamously alleged to have said) and a worthy sacrifice to push forward Communism.
As far a similarities to Ivan the Terrible, he did exhibit almost psychopathic tendencies of having no remorse for his policies and even taking joy in writing lists of political enemies he would order executed, however it can be argued that this was due to his zeal of preserving Communism and that he abused his power to carry out grudges. Ivan's terror was more due to self preservation in response to the Boyar's constant attacks against him during his reign. Stalin's only real enemies were the Western powers which he knew would leave him only as long as he didn't invade any nations allied with them.
Ivan had a soul. He knew he did terrible things and ugly things. He would bang his head on the floor in shame.
Stalin had no soul. These effeminates hence lived the present moment and did what they felt like a street walker. Hence they had no concept of good or bad or what they were doing was bad.