sustain vs substantiate

sustain and substantiate both are verbs.

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

As verbs, sustain and substantiate are synonyms defined as:

sustain and substantiate: establish or strengthen as with new evidence or facts

Other synonyms of sustain include affirm, confirm, corroborate, support.

sustain (verb)	substantiate (verb)
undergo (as of injuries and illnesses)	solidify, firm, or strengthen
establish or strengthen as with new evidence or facts	establish or strengthen as with new evidence or facts
admit as valid	make real or concrete; give reality or substance to
supply with necessities and support	represent in bodily form
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space