sleeping car vs wagon-lit

sleeping car and wagon-lit both are nouns.

Word	Noun	Adjective	Verb	Adverb
sleeping car	Yes	No	No	No
wagon-lit	Yes	No	No	No

As nouns, sleeping car and wagon-lit are synonyms defined as:

sleeping car and wagon-lit: a passenger car that has berths for sleeping

Other synonyms of sleeping car include sleeper.

sleeping car (noun)	wagon-lit (noun)
a passenger car that has berths for sleeping	a passenger car that has berths for sleeping