extension service vs university extension

extension service and university extension both are nouns.

Word	Noun	Adjective	Verb	Adverb
extension service	Yes	No	No	No
university extension	Yes	No	No	No

As nouns, extension service and university extension are synonyms defined as:

extension service and university extension: an educational opportunity provided by colleges and universities to people who are not enrolled as regular students

Other synonyms of extension service include extension.

extension service (noun)	university extension (noun)
an educational opportunity provided by colleges and universities to people who are not enrolled as regular students	an educational opportunity provided by colleges and universities to people who are not enrolled as regular students