I’ve played Age Of Mythology my whole life, what should I know before I start playing AoE2?

I’ve played AoM since probably around 2008 and love that game dearly, but the community recently feels dead, and I still haven’t played a single Age of Empires Game. I hear this one is the best, so which version is recommended? What are the major differences I should except (I have seen very very little about this game and all I know is that it’s super similar to AoM in a few ways. Thanks!