omnibus vs motorbus

omnibus and motorbus both are nouns.

Word	Noun	Adjective	Verb	Adverb
omnibus	Yes	Yes	No	No
motorbus	Yes	No	No	No

As nouns, omnibus and motorbus are synonyms defined as:

omnibus and motorbus: a vehicle carrying many passengers; used for public transport

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

omnibus (noun)	motorbus (noun)
a vehicle carrying many passengers; used for public transport	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

omnibus (adjective)	motorbus (adjective)
providing for many things at once