couchette vs bunk

couchette and bunk both are nouns.

Word	Noun	Adjective	Verb	Adverb
couchette	Yes	No	No	No
bunk	Yes	No	Yes	No

As nouns, bunk is a hypernym of couchette; that is, bunk is a word with a broader meaning than couchette:

Other hypernyms of couchette include berth, built in bed.

couchette (noun)	bunk (noun)
a compartment on a European passenger train; contains 4 to 6 berths for sleeping	a bed on a ship or train; usually in tiers
a sleeping berth in a couchette compartment.	a rough bed (as at a campsite)
	beds built one above the other
	a long trough for feeding cattle
	unacceptable behavior (especially ludicrously false statements)
	a message that seems to convey no meaning

couchette (verb)	bunk (verb)
	flee; take to one's heels; cut and run
	provide with a bunk
	avoid paying