As far as I understand Camus' notion of the Absurb, it is the idea that life ultimately has no purpose or that purpose is not attainable in any way. That being said, given Existentialism's anthropocentrism and its concomitant denial of transcendent absolutes, the conclusion that life lacks purpose and meaning is inescapable.
Nihilism follows inexorably therefrom.
It denies there is any such thing. For me, I have thought of purpose and meaning as being basically linked. I would think that from their position life doesn't have meaning, nor can it or anything else have meaning. Thus, God must be presupposed in order for any meaning at all. That much I'm reasonably sure of.