trolleybus vs autobus

trolleybus and autobus both are nouns.

Word	Noun	Adjective	Verb	Adverb
trolleybus	Yes	No	No	No
autobus	Yes	No	No	No

As nouns, autobus is a hypernym of trolleybus; that is, autobus is a word with a broader meaning than trolleybus:

trolleybus: a passenger bus with an electric motor that draws power from overhead wires
autobus: a vehicle carrying many passengers; used for public transport

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

trolleybus (noun)	autobus (noun)
a passenger bus with an electric motor that draws power from overhead wires	a vehicle carrying many passengers; used for public transport