police van vs patrol wagon

police van and patrol wagon both are nouns.

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

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

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

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