federal agency vs agency

federal agency and agency both are nouns.

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

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

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

federal agency (noun)	agency (noun)
an administrative unit of government	to have the ability to produce a particular effect or achieve an end
	an administrative unit of government
	a business or organization that provides a particular service, especially the mediation of transactions between two parties
	the state of serving as an official and authorized delegate or agent
	the state of being in action or exerting power