USAF vs federal agency

USAF and federal agency both are nouns.

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

As nouns, federal agency is a hypernym of USAF; that is, federal 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
federal agency: an administrative unit of government

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

USAF (noun)	federal 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