fanny vs vulva

fanny and vulva both are nouns.

Word	Noun	Adjective	Verb	Adverb
fanny	Yes	No	No	No
vulva	Yes	No	No	No

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

Other hyponyms of fanny include minge, cunt, puss, pussy, slit, snatch, twat.

fanny (noun)	vulva (noun)
the fleshy part of the human body that you sit on	external parts of the female genitalia
external female sex organs