denim vs Levi's

denim and Levi's both are nouns.

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

As nouns, Levi's is a hyponym of denim; that is, Levi's is a word with a more specific, narrower meaning than denim:

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

Other hyponyms of denim include levis, distressed jeans.

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