option vs casting

option and casting both are nouns.

Word	Noun	Adjective	Verb	Adverb
option	Yes	No	No	No
casting	Yes	No	No	No

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

option (noun)	casting (noun)
the act of choosing or selecting	the act of creating something by casting it in a mold
one of a number of things from which only one can be chosen	the act of throwing a fishing line out over the water by means of a rod and reel
the right to buy or sell property at an agreed price; the right is purchased and if it is not exercised by a stated date the money is forfeited	the choice of actors to play particular roles in a play or movie
	object formed by a mold