parlor car vs parlour car

parlor car and parlour car both are nouns.

Word	Noun	Adjective	Verb	Adverb
parlor car	Yes	No	No	No
parlour car	Yes	No	No	No

As nouns, parlor car and parlour car are synonyms defined as:

parlor car and parlour car: a passenger car for day travel; you pay extra fare for individual chairs

Other synonyms of parlor car include chair car, drawing-room car, palace car.

parlor car (noun)	parlour car (noun)
a passenger car for day travel; you pay extra fare for individual chairs	a passenger car for day travel; you pay extra fare for individual chairs