sepulcher vs crypt

sepulcher and crypt both are nouns.

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

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

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

Other hyponyms of sepulcher include mausoleum, monument, repository, burial vault, vault.

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