police car vs patrol car

police car and patrol car both are nouns.

Word	Noun	Adjective	Verb	Adverb
police car	Yes	No	No	No
patrol car	Yes	No	No	No

As nouns, police car and patrol car are synonyms defined as:

police car and patrol car: a car in which policemen cruise the streets; equipped with radiotelephonic communications to headquarters

Other synonyms of police car include cruiser, police cruiser, prowl car, squad car.

police car (noun)	patrol car (noun)
a car in which policemen cruise the streets; equipped with radiotelephonic communications to headquarters	a car in which policemen cruise the streets; equipped with radiotelephonic communications to headquarters