prop vs sustain

prop is a noun but sustain is not a noun.

Word	Noun	Adjective	Verb	Adverb
prop	Yes	No	Yes	No
sustain	No	No	Yes	No

As verbs, sustain is a hypernym of prop; that is, sustain is a word with a broader meaning than prop:

Other hypernyms of prop include hold, hold up, support.

prop (noun)	sustain (noun)
a support placed beneath or against something to keep it from shaking or falling
a propeller that rotates to push against air
any movable articles or objects used on the set of a play or movie

prop (verb)	sustain (verb)
support by placing against something solid or rigid	undergo (as of injuries and illnesses)
	establish or strengthen as with new evidence or facts
	admit as valid
	supply with necessities and support
	provide with nourishment
	be the physical support of; carry the weight of
	lengthen or extend in duration or space