National Guard Bureau vs office

National Guard Bureau and office both are nouns.

Word	Noun	Adjective	Verb	Adverb
National Guard Bureau	Yes	No	No	No
office	Yes	No	No	No

As nouns, office is a hypernym of National Guard Bureau; that is, office is a word with a broader meaning than National Guard Bureau:

National Guard Bureau: the agency that administers the Army National Guard and the Air National Guard; provides liaison between the Army and the Air Force and various National Guard units
office: an administrative unit of government

Other hypernyms of National Guard Bureau include agency, authority, bureau, federal agency, government agency.

National Guard Bureau (noun)	office (noun)
the agency that administers the Army National Guard and the Air National Guard; provides liaison between the Army and the Air Force and various National Guard units	a religious rite or service prescribed by ecclesiastical authorities
	the actions and activities assigned to or required or expected of a person or group
	a job in an organization
	place of business where professional or clerical duties are performed
	professional or clerical workers in an office
	an administrative unit of government
	(of a government or government official) holding an office means being in power