sleeping car vs coach

sleeping car and coach both are nouns.

Word	Noun	Adjective	Verb	Adverb
sleeping car	Yes	No	No	No
coach	Yes	No	Yes	No

As nouns, coach is a hypernym of sleeping car; that is, coach is a word with a broader meaning than sleeping car:

Other hypernyms of sleeping car include carriage, passenger car.

sleeping car (noun)	coach (noun)
a passenger car that has berths for sleeping	a carriage pulled by four horses with one driver
	a railcar where passengers ride
	a vehicle carrying many passengers; used for public transport
	a person who gives private instruction (as in singing, acting, etc.)
	(sports) someone in charge of training an athlete or a team

sleeping car (verb)	coach (verb)
	teach and supervise (someone); act as a trainer or coach (to), as in sports
	drive or operate a coach or carriage