what is Leninism ? and what is the difference between Stalinism and Leninism

https://www.sociologygroup.com/leninism-simple-terms/

“He feared that the proletariats would be diverted easily in their motive to dethrone capitalism. This was the point where Leninism differed from Marxism. For the Marxists, material conditions were enough to facilitate the workers to realize their need for revolting.”