jeans vs blue jeans

jeans and blue jeans both are nouns.

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

As nouns, jeans and blue jeans are synonyms defined as:

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

Other synonyms of jeans include denim.

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