necromancy vs demonism

necromancy and demonism both are nouns.

Word	Noun	Adjective	Verb	Adverb
necromancy	Yes	No	No	No
demonism	Yes	No	No	No

As nouns, demonism is a hyponym of necromancy; that is, demonism is a word with a more specific, narrower meaning than necromancy:

necromancy: the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world
demonism: a belief in and reverence for devils (especially Satan)

Other hyponyms of necromancy include witchcraft, witchery, bewitchment, enchantment, diabolism, Satanism, obiism.

necromancy (noun)	demonism (noun)
conjuring up the dead, especially for prophesying	a belief in and reverence for devils (especially Satan)
the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world