maiden vs girl

maiden and girl both are nouns.

Word	Noun	Adjective	Verb	Adverb
maiden	Yes	Yes	No	No
girl	Yes	No	No	No

As nouns, girl is a hypernym of maiden; that is, girl is a word with a broader meaning than maiden:

Other hypernyms of maiden include fille, miss, missy, young lady, young woman.

maiden (noun)	girl (noun)
an unmarried girl (especially a virgin)	a young female
(cricket) an over in which no runs are scored	a girl or young woman with whom a man is romantically involved
	a youthful female person
	a friendly informal reference to a grown woman
	a female human offspring

maiden (adjective)	girl (adjective)
serving to set in motion