GPO vs bureau

GPO and bureau both are nouns.

Word	Noun	Adjective	Verb	Adverb
GPO	Yes	No	No	No
bureau	Yes	No	No	No

As nouns, bureau is a hypernym of GPO; that is, bureau is a word with a broader meaning than GPO:

GPO: an agency of the legislative branch that provides printing and binding services for Congress and the departments and establishments of the federal government
bureau: an administrative unit of government

Other hypernyms of GPO include agency, authority, federal agency, government agency, office.

GPO (noun)	bureau (noun)
an agency of the legislative branch that provides printing and binding services for Congress and the departments and establishments of the federal government	furniture with drawers for keeping clothes
	an administrative unit of government