I don't think I'm going to tackle this question right now, but a question of clarification in case someone else comes along: First of all by Castrism I assumed you mean Castro's Cuba. Second of all, by similarities, which ones are you thinking of in particular?

Regardless, you might want to check out these fantastic answers by /u/depanneur that focused on ideology: https://www.reddit.com/r/AskHistorians/comments/5i1onm/why_are_communism_and_fascism_generally/db73312/

https://www.reddit.com/r/AskHistorians/comments/22ox1w/what_is_fascism/cgoz902/