burial vault vs burial chamber

burial vault and burial chamber both are nouns.

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

As nouns, burial chamber is a hypernym of burial vault; that is, burial chamber is a word with a broader meaning than burial vault:

Other hypernyms of burial vault include sepulcher, sepulchre, sepulture.

burial vault (noun)	burial chamber (noun)
a burial chamber (usually underground)	a chamber that is used as a grave