university extension vs extension service

university extension and extension service both are nouns.

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

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

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

Other synonyms of university extension include extension.

university extension (noun)	extension service (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