overnighter vs traveling bag

overnighter and traveling bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
overnighter	Yes	No	No	No
traveling bag	Yes	No	No	No

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

overnighter: a small traveling bag to carry clothing and accessories for staying overnight
traveling bag: a portable rectangular container for carrying clothes

Other hypernyms of overnighter include bag, grip, suitcase, travelling bag.

overnighter (noun)	traveling bag (noun)
a small traveling bag to carry clothing and accessories for staying overnight	a portable rectangular container for carrying clothes
a guest who stays overnight