police car vs squad car

police car and squad car both are nouns.

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

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

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

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

police car (noun)	squad 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