How does microblogging on Lemmy communities work?

I'm guessing it has something to do with mastodon, since microblogging is interoperable with mastodon like how threads are interoperable with lemmy.

Example post:
https://kbin.social/m/[email protected]/p/434431

I can see this post on beehaw here:
https://beehaw.org/post/565892

But next to it in [email protected] are threads that show up in the threads section of kbin.social/m/[email protected]

How are threads and microblogs distinguished on different instances if they're both interoperable with both lemmy and mastodon like this appears to be? How can you access the general mastodon feed from kbin?