The disease AIDS (acquired immune deficiency syndrome) is the final stage of HIV (human immonidifiency virus). HIV attacks the immune system which compromises the body's ability to fight infection. AIDS can be the result in which opportunistic microorganisms can multiply in the body causing all sorts of diseases that the body can't fight.
Aids as in teaching aids are educational resources teachers use to help students learn. Aid in this sense means "help" or "assist."