government agency vs bureau

government agency and bureau both are nouns.

Word	Noun	Adjective	Verb	Adverb
government agency	Yes	No	No	No
bureau	Yes	No	No	No

As nouns, government agency and bureau are synonyms defined as:

Other synonyms of government agency include agency, authority, federal agency, office.

government agency (noun)	bureau (noun)
an administrative unit of government	furniture with drawers for keeping clothes
	an administrative unit of government