Dos AdBlock Plus simply hide ad's (Ie. most of the stuff attached to them are running in the background), or dos it actually block them from ever loading like uBO?

Side note: I do not use AdBlock Plus, I'm asking cos I claimed that AdBlock Plus only hides ad's as opposed to blocking them, and when asked to prove it, I realized I did'nt have any besides that I was told that a long time ago (witch is not proof) so I'm asking here in order to ether confirm whether or not I was right or wrong.

ad adblock dos hide privacy