diner vs dining compartment

diner and dining compartment both are nouns.

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

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

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

Other synonyms of diner include buffet car, dining car.

diner (noun)	dining compartment (noun)
a passenger car where food is served in transit	a passenger car where food is served in transit
a restaurant that resembles a dining car
a person eating a meal (especially in a restaurant)