bureau vs government agency

bureau and government agency both are nouns.

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

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

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

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