inheritress vs adult female

inheritress and adult female both are nouns.

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

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

Other hypernyms of inheritress include heir, heritor, inheritor, woman.

inheritress (noun)	adult female (noun)
a female heir	an adult female person (as opposed to a man)