sempstress vs adult female

sempstress and adult female both are nouns.

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

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

Other hypernyms of sempstress include dressmaker, garment-worker, garment worker, garmentmaker, woman.

sempstress (noun)	adult female (noun)
a woman who makes or mends dresses	an adult female person (as opposed to a man)