autobus vs passenger vehicle

autobus and passenger vehicle both are nouns.

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

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

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

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

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