berth vs couchette

berth and couchette both are nouns.

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

As nouns, couchette is a hyponym of berth; that is, couchette is a word with a more specific, narrower meaning than berth:

Other hyponyms of berth include lower, lower berth, upper, upper berth.

berth (noun)	couchette (noun)
a job in an organization	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 place where a craft can be made fast

berth (verb)	couchette (verb)
secure in or as if in a berth or dock
come into or dock at a wharf
provide with a berth