slip carriage vs railroad car

slip carriage and railroad car both are nouns.

Word	Noun	Adjective	Verb	Adverb
slip carriage	Yes	No	No	No
railroad car	Yes	No	No	No

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

slip carriage: a railway car at the end of the train; it can be detached without stopping the train
railroad car: a wheeled vehicle adapted to the rails of railroad

Other hypernyms of slip carriage include car, railcar, railway car.

slip carriage (noun)	railroad car (noun)
a railway car at the end of the train; it can be detached without stopping the train	a wheeled vehicle adapted to the rails of railroad