cabin car vs railroad car

cabin car and railroad car both are nouns.

Word	Noun	Adjective	Verb	Adverb
cabin car	Yes	No	No	No
railroad car	Yes	No	No	No

As nouns, railroad car is a hypernym of cabin car; that is, railroad car is a word with a broader meaning than cabin car:

cabin car: a car on a freight train for use of the train crew; usually the last car on the train
railroad car: a wheeled vehicle adapted to the rails of railroad

Other hypernyms of cabin car include car, railcar, railway car.

cabin car (noun)	railroad car (noun)
a car on a freight train for use of the train crew; usually the last car on the train	a wheeled vehicle adapted to the rails of railroad