van vs railroad car

van and railroad car both are nouns.

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

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

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

van (noun)	railroad car (noun)
a truck with an enclosed cargo space	a wheeled vehicle adapted to the rails of railroad
a camper equipped with living quarters
(Great Britain) a closed railroad car that carries baggage or freight
the leading units moving at the head of an army
any creative group active in the innovation and application of new concepts and techniques in a given field (especially in the arts)