trolley coach vs omnibus

trolley coach and omnibus both are nouns.

Word	Noun	Adjective	Verb	Adverb
trolley coach	Yes	No	No	No
omnibus	Yes	Yes	No	No

As nouns, omnibus is a hypernym of trolley coach; that is, omnibus is a word with a broader meaning than trolley coach:

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

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

trolley coach (noun)	omnibus (noun)
a passenger bus with an electric motor that draws power from overhead wires	a vehicle carrying many passengers; used for public transport
	an anthology of articles on a related subject or an anthology of the works of a single author

trolley coach (adjective)	omnibus (adjective)
	providing for many things at once