casting vs death mask

casting and death mask both are nouns.

Word	Noun	Adjective	Verb	Adverb
casting	Yes	No	No	No
death mask	Yes	No	No	No

As nouns, death mask is a hyponym of casting; that is, death mask is a word with a more specific, narrower meaning than casting:

Other hyponyms of casting include block, cylinder block, engine block, life mask.

casting (noun)	death mask (noun)
the act of creating something by casting it in a mold	a cast taken from the face of a dead person
the act of throwing a fishing line out over the water by means of a rod and reel
the choice of actors to play particular roles in a play or movie
object formed by a mold