omnibus vs autobus

omnibus and autobus both are nouns.

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

As nouns, omnibus and autobus are synonyms defined as:

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

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

omnibus (noun)	autobus (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)	autobus (adjective)
providing for many things at once