passenger vehicle vs roof

passenger vehicle and roof both are nouns.

Word	Noun	Adjective	Verb	Adverb
passenger vehicle	Yes	No	No	No
roof	Yes	No	Yes	No

passenger vehicle (noun)	roof (noun)
a vehicle carrying many passengers; used for public transport	a protective covering that covers or forms the top of a building
	protective covering on top of a motor vehicle
	an upper limit on what is allowed
	the inner top surface of a covered area or hollow space

passenger vehicle (verb)	roof (verb)
	provide a building with a roof; cover a building with a roof