smoking car vs smoking carriage

smoking car and smoking carriage both are nouns.

Word	Noun	Adjective	Verb	Adverb
smoking car	Yes	No	No	No
smoking carriage	Yes	No	No	No

As nouns, smoking car and smoking carriage are synonyms defined as:

smoking car and smoking carriage: a passenger car for passengers who wish to smoke

Other synonyms of smoking car include smoker, smoking compartment.

smoking car (noun)	smoking carriage (noun)
a passenger car for passengers who wish to smoke	a passenger car for passengers who wish to smoke