NCDC vs government agency

NCDC and government agency both are nouns.

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

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

NCDC: the part of NOAA that maintains the world's largest active archive of weather data
government agency: an administrative unit of government

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

NCDC (noun)	government agency (noun)
the part of NOAA that maintains the world's largest active archive of weather data	an administrative unit of government