Levi's vs jeans

Levi's and jeans both are nouns.

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

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

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

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

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