fancy woman vs adult female

fancy woman and adult female both are nouns.

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

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

fancy woman: an adulterous woman; a woman who has an ongoing extramarital sexual relationship with a man
adult female: an adult female person (as opposed to a man)

Other hypernyms of fancy woman include lover, woman.

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

Other hypernyms of fancy woman include woman.

fancy woman (noun)	adult female (noun)
an adulterous woman; a woman who has an ongoing extramarital sexual relationship with a man	an adult female person (as opposed to a man)
a woman who engages in sexual intercourse for money