Bureau of the Census vs agency

Bureau of the Census and agency both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bureau of the Census	Yes	No	No	No
agency	Yes	No	No	No

As nouns, agency is a hypernym of Bureau of the Census; that is, agency is a word with a broader meaning than Bureau of the Census:

Bureau of the Census: the bureau of the Commerce Department responsible for taking the census; provides demographic information and analyses about the population of the United States
agency: an administrative unit of government

Other hypernyms of Bureau of the Census include authority, bureau, federal agency, government agency, office.

Bureau of the Census (noun)	agency (noun)
the bureau of the Commerce Department responsible for taking the census; provides demographic information and analyses about the population of the United States	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