crazy vs maniac

crazy and maniac both are nouns.

Word	Noun	Adjective	Verb	Adverb
crazy	Yes	Yes	No	No
maniac	Yes	Yes	No	No

As nouns, maniac is a hypernym of crazy; that is, maniac is a word with a broader meaning than crazy:

Other hypernyms of crazy include lunatic.

crazy (noun)	maniac (noun)
someone deranged and possibly dangerous	an insane person
	a person who has an obsession with or excessive enthusiasm for something

crazy (adjective)	maniac (adjective)
intensely enthusiastic about or preoccupied with	wildly disordered
possessed by inordinate excitement
foolish; totally unsound
affected with madness or insanity
bizarre or fantastic