Does anyone know what the difficulty setting actual changes?

I tried on the darksiders Wikia, but they only claim it getting harder with no information on how.

Is it just slower experience gain or are the enemies harder as well?
More trash-mobs?

Nightmare -> hardcore mode?
Apocalyptic -> monster more health and damage.

Drops are affected by the setting as well?*
http://gaming.stackexchange.com/questions/80764/whats-the-difference-between-the-normal-and-apocalyptic-difficulties

*Like it was in Diablo2?