The order they used to work is reflect (not in skyrim), absorb magic, resist magic, resist element. magic resist is better than elemental resist because yes it works on elements and may block other spells like paralyze. magic absorb is best for non summoners and magic absorb stacks with magic resist. absorb cap is 80 % and resist cap is 85 %. Between the 2 caps only 3% of magic gets through. FYI be careful with magic absorb and an atronach summoner: you can absorb your own spell thus not conjuring anything while you try try again and get hit by enemies. from what i hear necromancers don't have this problem.
so basically absorb is best, resist is great and elemental resist is useless IMO.