policewoman vs adult female

policewoman and adult female both are nouns.

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

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

Other hypernyms of policewoman include officer, police officer, woman.

policewoman (noun)	adult female (noun)
a woman policeman	an adult female person (as opposed to a man)