service firm vs service agency

service firm and service agency both are nouns.

Word	Noun	Adjective	Verb	Adverb
service firm	Yes	No	No	No
service agency	Yes	No	No	No

As nouns, service firm and service agency are synonyms defined as:

service firm and service agency: a business that makes its facilities available to others for a fee; achieves economy of scale

Other synonyms of service firm include service bureau.

service firm (noun)	service agency (noun)
a business that makes its facilities available to others for a fee; achieves economy of scale	a business that makes its facilities available to others for a fee; achieves economy of scale