police van vs paddy wagon

police van and paddy wagon both are nouns.

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

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

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

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