sepulcher vs burial chamber

sepulcher and burial chamber both are nouns.

Word	Noun	Adjective	Verb	Adverb
sepulcher	Yes	No	No	No
burial chamber	Yes	No	No	No

As nouns, sepulcher and burial chamber are synonyms defined as:

Other synonyms of sepulcher include sepulchre, sepulture.

sepulcher (noun)	burial chamber (noun)
a chamber that is used as a grave	a chamber that is used as a grave