police wagon vs police van

police wagon and police van both are nouns.

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

As nouns, police wagon and police van are synonyms defined as:

Other synonyms of police wagon include black Maria, paddy wagon, patrol wagon, wagon.

police wagon (noun)	police van (noun)
van used by police to transport prisoners	van used by police to transport prisoners