passenger vehicle vs autobus

passenger vehicle and autobus both are nouns.

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

As nouns, passenger vehicle and autobus are synonyms defined as:

passenger vehicle and autobus: a vehicle carrying many passengers; used for public transport

Other synonyms of passenger vehicle include bus, charabanc, coach, double-decker, jitney, motorbus, motorcoach, omnibus.

passenger vehicle (noun)	autobus (noun)
a vehicle carrying many passengers; used for public transport	a vehicle carrying many passengers; used for public transport