farm building vs building

farm building and building both are nouns.

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

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

farm building: a building on a farm
building: a structure that has a roof and walls and stands more or less permanently in one place

Other hypernyms of farm building include edifice.

farm building (noun)	building (noun)
a building on a farm	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