Levi's vs denim

Levi's and denim both are nouns.

Word	Noun	Adjective	Verb	Adverb
Levi's	Yes	No	No	No
denim	Yes	No	No	No

As nouns, denim is a hypernym of Levi's; that is, denim is a word with a broader meaning than Levi's:

Levi's: a popular brand of jeans
denim: (used in the plural) close-fitting trousers of heavy denim for manual work or casual wear

Other hypernyms of Levi's include blue jeans, jeans.

Levi's (noun)	denim (noun)
a popular brand of jeans	a coarse durable twill-weave cotton fabric
	(used in the plural) close-fitting trousers of heavy denim for manual work or casual wear