couchette vs compartment

couchette and compartment both are nouns.

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

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

couchette: a compartment on a European passenger train; contains 4 to 6 berths for sleeping
compartment: a partitioned section, chamber, or separate room within a larger enclosed area

couchette (noun)	compartment (noun)
a compartment on a European passenger train; contains 4 to 6 berths for sleeping	a partitioned section, chamber, or separate room within a larger enclosed area
a sleeping berth in a couchette compartment.	a space into which an area is subdivided