Those usually refer to messages sent to the other guy.

Say you have the default setting that allows 3 uploads per user.

Someone browses you, and chooses 4 of your files: the fourth, or a duplicate request, gets the "limit reached" message.

Say they choose 100: a lot of them will get the "greedy" message from you, and your server will ignore any more requests from their client for <don't know how long>

If the client starts a download, then kills it or quits, thus refusing any more packets for that file, you get the notification that the upload was "interrupted"

There are more variations and cases I'm sure, but you get the idea . . .

For more and better info, watch for posts by sberlin or one of the other developers. The code is always improving, so today's answers might change (I hope so--I'd like to see the greedy request held queued by the client, who would then only send respectful requests)