burial chamber vs tomb

burial chamber and tomb both are nouns.

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

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

burial chamber: a chamber that is used as a grave
tomb: a place for the burial of a corpse (especially beneath the ground and marked by a tombstone)

Other hypernyms of burial chamber include chamber, grave.

burial chamber (noun)	tomb (noun)
a chamber that is used as a grave	a place for the burial of a corpse (especially beneath the ground and marked by a tombstone)