dining compartment vs dining car

dining compartment and dining car both are nouns.

Word	Noun	Adjective	Verb	Adverb
dining compartment	Yes	No	No	No
dining car	Yes	No	No	No

As nouns, dining compartment and dining car are synonyms defined as:

dining compartment and dining car: a passenger car where food is served in transit

Other synonyms of dining compartment include buffet car, diner.

dining compartment (noun)	dining car (noun)
a passenger car where food is served in transit	a passenger car where food is served in transit