I think they're basically the same thing. But for some reason, I associate "estrange" with family, like "an estranged father" and it's almost always used as an adjective. "Alienate" is a more general term and is a more common verb than "estrange."

Have you tried a good dictionary first? It just seems to me that that's a good place to start and then to come here if clarification is needed. I don't mean to sound harsh but it will stick in your mind better if you go this route, in my opinion.

You're welcome! If you want to do lessons with me some times, let me know!