pin-up vs adult female

pin-up and adult female both are nouns.

Word	Noun	Adjective	Verb	Adverb
pin-up	Yes	No	No	No
adult female	Yes	No	No	No

As nouns, adult female is a hypernym of pin-up; that is, adult female is a word with a broader meaning than pin-up:

Other hypernyms of pin-up include photographer's model, woman.

pin-up (noun)	adult female (noun)
a very pretty girl who works as a photographer's model	an adult female person (as opposed to a man)