USAF vs government agency

USAF and government agency both are nouns.

Word	Noun	Adjective	Verb	Adverb
USAF	Yes	No	No	No
government agency	Yes	No	No	No

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

USAF: the airforce of the United States of America; the agency that defends the United States through control and exploitation of air and space
government agency: an administrative unit of government

Other hypernyms of USAF include agency, authority, bureau, federal agency, office.

USAF (noun)	government agency (noun)
the airforce of the United States of America; the agency that defends the United States through control and exploitation of air and space	an administrative unit of government