maid of honor vs adult female

maid of honor and adult female both are nouns.

Word	Noun	Adjective	Verb	Adverb
maid of honor	Yes	No	No	No
adult female	Yes	No	No	No

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

Other hypernyms of maid of honor include attendant, attender, tender, woman.

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