van vs railway car

van and railway car both are nouns.

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

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

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

van (noun)	railway 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)