blue jeans vs levis

blue jeans and levis both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue jeans	Yes	No	No	No
levis	Yes	No	No	No

As nouns, levis is a hyponym of blue jeans; that is, levis is a word with a more specific, narrower meaning than blue jeans:

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

Other hyponyms of blue jeans include Levi's, distressed jeans.

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