bureau vs federal agency

bureau and federal agency both are nouns.

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

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

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

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