garment bag vs suitcase

garment bag and suitcase both are nouns.

Word	Noun	Adjective	Verb	Adverb
garment bag	Yes	No	No	No
suitcase	Yes	No	No	No

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

Other hypernyms of garment bag include bag, grip, traveling bag, travelling bag.

garment bag (noun)	suitcase (noun)
a suitcase that unfolds to be hung up	a portable rectangular container for carrying clothes