police van vs van

police van and van both are nouns.

Word	Noun	Adjective	Verb	Adverb
police van	Yes	No	No	No
van	Yes	No	No	No

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

police van (noun)	van (noun)
van used by police to transport prisoners	a truck with an enclosed cargo space
	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)