smoking compartment vs smoking car

smoking compartment and smoking car both are nouns.

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

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

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

Other synonyms of smoking compartment include smoker, smoking carriage.

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