crypt vs sepulcher

crypt and sepulcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
crypt	Yes	No	No	No
sepulcher	Yes	No	No	No

As nouns, sepulcher is a hypernym of crypt; that is, sepulcher is a word with a broader meaning than crypt:

crypt: a cellar or vault or underground burial chamber (especially beneath a church)
sepulcher: a chamber that is used as a grave

Other hypernyms of crypt include burial chamber, sepulchre, sepulture.

crypt (noun)	sepulcher (noun)
a cellar or vault or underground burial chamber (especially beneath a church)	a chamber that is used as a grave