adult female vs female

adult female and female both are nouns.

Word	Noun	Adjective	Verb	Adverb
adult female	Yes	No	No	No
female	Yes	Yes	No	No

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

Other hypernyms of adult female include adult, grownup, female person.

adult female (noun)	female (noun)
an adult female person (as opposed to a man)	an animal that produces gametes (ova) that can be fertilized by male gametes (spermatozoa)
	a person who belongs to the sex that can have babies

adult female (adjective)	female (adjective)
	being the sex (of plant or animal) that produces fertilizable gametes (ova) from which offspring develop
	for or pertaining to or composed of women or girls
	characteristic of or peculiar to a woman