Yes, it means both are not present. HIV has to be present for there to be Aids so if you have Aids, you are HIV positive. However, if you are HIV positive, you do not necessarily have Aids.

Think of it like all the germs in and around us and some people catch something but other people there at the same time do not? It depends on your immune system if the HIV turns into Aids but you have to have the HIV virus, first. If you are HIV negative, then that virus is not in you so you can't "catch" the Aids no matter what.