Hoping this is correct. Whats a Thread under a magazine, especially vs. a Microblog

And why must I create a new 'article' to make a thread and not a post - which I think makes a new microblog.

I'm coming from a Mastodon POV, I run my own instance and have a pretty good idea (I think) about how federation works. The way ActivityPub is used is close enough to be familiar but also... not; very uncanny valley.

Additionally, if upvotes are favourites, what are downvotes? and how are they federated?