Made a post on a shitjustworks community some time ago; from what I can see on this account, it got no attention at all. However, recently I saw from a different account on a different instance that said post did get attention, including upvotes and answers. I'm a little confused now on what's happening. Is this instance not federated with sh.itjustworks?
On a tangentially related but irrelevant to this thread note, I originally made this account because I thought it'd be apt to keep my authorial things and contributions to this instance's communities in this instance; should I continue to do so or just keep everything on my main account?
Federation is when two servers agree to share information using the same protocol. The best example of this is email. Different providers can send emails in the same format to different servers, regardless of whether they have the same owner because they use the same protocol. This is federation. Federation also has the plus of being able to choose which servers you want to share information with.
You're probably right that one instance isn't federated, or another option is that one server has an older record of a post than another and hasn't been updated yet for some reason.