bridesmaid vs adult female

bridesmaid and adult female both are nouns.

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

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

Other hypernyms of bridesmaid include attendant, attender, tender, woman.

bridesmaid (noun)	adult female (noun)
an unmarried woman who attends the bride at a wedding	an adult female person (as opposed to a man)