NGB vs federal agency

NGB and federal agency both are nouns.

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

As nouns, federal agency is a hypernym of NGB; that is, federal agency is a word with a broader meaning than NGB:

NGB: 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
federal agency: an administrative unit of government

Other hypernyms of NGB include agency, authority, bureau, government agency, office.

NGB (noun)	federal agency (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	an administrative unit of government