dining car vs dining compartment

dining car and dining compartment both are nouns.

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

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

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

Other synonyms of dining car include buffet car, diner.

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