onanism vs autoerotism

onanism and autoerotism both are nouns.

Word	Noun	Adjective	Verb	Adverb
onanism	Yes	No	No	No
autoerotism	Yes	No	No	No

As nouns, autoerotism is a hypernym of onanism; that is, autoerotism is a word with a broader meaning than onanism:

onanism: manual stimulation of the genital organs (of yourself or another) for sexual pleasure
autoerotism: using your own body as a sexual object

Other hypernyms of onanism include autoeroticism.

onanism (noun)	autoerotism (noun)
manual stimulation of the genital organs (of yourself or another) for sexual pleasure	using your own body as a sexual object
a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation