lemmy.world and beehaw.org are defederated. However, this doesn't mean that you can't see beehaw posts as a lemmy.world user, or vice versa. But (let's say you're a lemmy.world user) if you comment on a beehaw post, you're commenting on a replicated version of the post that is hosted on lemmy.world. It is not synced with the original post hosted on beehaw, and you will only be able to see comments from other lemmy.world users and comments from before beehaw defederated.

[–] Gex@discuss.tchncs.de 2 points 1 year ago (1 children)

Thanks that makes sense. I understand that if I'm on a third instance that is federated with both lemmy.world and beehaw.org, and I click on a beehaw.org post then I would not be able to see comments from lemmy.world users. But I would be able to see comments from beehaw.org users and they would see comments from my instance.

[–] beanz@lemmy.world 2 points 1 year ago

Yep the original post on the beehaw instance is like a master record of the post that lives on their server and only their users and users from federated instances can interact with it. Meanwhile the act of a lemmy.world user subscribing to a given beehaw community triggers the lemmy.world instance to archive posts there and create separate self-contained records of them which only lemmy.world users can interact with