double-decker vs jitney

double-decker and jitney both are nouns.

Word	Noun	Adjective	Verb	Adverb
double-decker	Yes	No	No	No
jitney	Yes	No	No	No

As nouns, double-decker and jitney are synonyms defined as:

double-decker and jitney: a vehicle carrying many passengers; used for public transport

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

double-decker (noun)	jitney (noun)
a vehicle carrying many passengers; used for public transport	a vehicle carrying many passengers; used for public transport