valise vs overnight bag

valise and overnight bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
valise	Yes	No	No	No
overnight bag	Yes	No	No	No

As nouns, overnight bag is a hypernym of valise; that is, overnight bag is a word with a broader meaning than valise:

valise: a small overnight bag for short trips
overnight bag: a small traveling bag to carry clothing and accessories for staying overnight

Other hypernyms of valise include overnight case, overnighter.

valise (noun)	overnight bag (noun)
a small overnight bag for short trips	a small traveling bag to carry clothing and accessories for staying overnight