Lifekeeping - [Caster can prevent the soul of a "dead" body from leaving, thus preventing an actual death and enabling the fallen beeing to be restored via simple bodily repairs]
In my book it cant get much clearer than that.
The spell stops the soul from saying "Ah, bother, this one is dead. Well, I'm outta here". i.e stops it from doing what it normally does when a body dies. The soul is convinced to hang on a bit longer.
Absolution is a spell that ripps the soul from the living body. It does not ask what the soul wants, it ripps it, kicking and screaming, from the body. The two spells are not related.