inheritrix vs adult female

inheritrix and adult female both are nouns.

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

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

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

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