daygirl vs day boarder

daygirl and day boarder both are nouns.

Word	Noun	Adjective	Verb	Adverb
daygirl	Yes	No	No	No
day boarder	Yes	No	No	No

As nouns, day boarder is a hypernym of daygirl; that is, day boarder is a word with a broader meaning than daygirl:

daygirl: a day boarder who is a girl
day boarder: a schoolchild at a boarding school who has meals at school but sleeps at home

daygirl (noun)	day boarder (noun)
a day boarder who is a girl	a schoolchild at a boarding school who has meals at school but sleeps at home