A lot of black metal is about paganism and fantasy rather than blasphemy. Look at Emperor, a lot of Dark Throne, Burzum, Immortal, In the Woods, a lot of the Norwegian scene.
Death metal seems to me to be mostly about a hatred of morality and holiness, whether it be mocking respect for human life with gory images and murder fantasies, or more straightforward Deicide-like blasphemetal.
Just my opinions on the matter.
