upstairs vs building

upstairs and building both are nouns.

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

upstairs (noun)	building (noun)
the part of a building above the ground floor	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

upstairs (adjective)	building (adjective)
on or of upper floors of a building

upstairs (adverb)	building (adverb)
on a floor above
with respect to the mind