borrower's card vs library card

borrower's card and library card both are nouns.

Word	Noun	Adjective	Verb	Adverb
borrower's card	Yes	No	No	No
library card	Yes	No	No	No

As nouns, borrower's card and library card are synonyms defined as:

borrower's card and library card: a card certifying the bearer's right to use the library

borrower's card (noun)	library card (noun)
a card certifying the bearer's right to use the library	a card certifying the bearer's right to use the library