blue jeans vs trousers

blue jeans and trousers both are nouns.

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

As nouns, trousers is a hypernym of blue jeans; that is, trousers is a word with a broader meaning than blue jeans:

blue jeans: (used in the plural) close-fitting trousers of heavy denim for manual work or casual wear
trousers: (usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately

Other hypernyms of blue jeans include pair of trousers, pant, workwear.

blue jeans (noun)	trousers (noun)
(used in the plural) close-fitting trousers of heavy denim for manual work or casual wear	(usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately