government building vs building

government building and building both are nouns.

Word	Noun	Adjective	Verb	Adverb
government building	Yes	No	No	No
building	Yes	No	No	No

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

government building: a building that houses a branch of government
building: a structure that has a roof and walls and stands more or less permanently in one place

Other hypernyms of government building include edifice.

government building (noun)	building (noun)
a building that houses a branch of government	the act of constructing something
	the commercial activity involved in repairing old structures or constructing new ones
	a structure that has a roof and walls and stands more or less permanently in one place
	the occupants of a building