Stalinism evolved out of Leninism, it grew as a cult around Joseph Stalin out of Lenin's godlike image once he passed away in 1924. It differs in a sense of how you look at it, if in a revisionist form you'd see a break between the two types in how each person used his power to run the centralised USSR. Both idealogies evolved from Marxism and the clas struggle, except their leanings towards communism were given more focus than Karl Marx did when he made the theory.
They are proper forms of Communism although from my point of view, Lenin's form of government was closer to Communism just before his death as he idealized equality and a utopian communist world in Russia. Stalin appeared to want the same aims, but you could argue he manipulated Leninism to his advantage. More.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.