subroutine library vs program library

subroutine library and program library both are nouns.

Word	Noun	Adjective	Verb	Adverb
subroutine library	Yes	No	No	No
program library	Yes	No	No	No

As nouns, subroutine library and program library are synonyms defined as:

subroutine library and program library: (computing) a collection of standard programs and subroutines that are stored and available for immediate use

Other synonyms of subroutine library include library.

subroutine library (noun)	program library (noun)
(computing) a collection of standard programs and subroutines that are stored and available for immediate use	(computing) a collection of standard programs and subroutines that are stored and available for immediate use