substantiate vs sustain

substantiate and sustain both are verbs.

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

As verbs, substantiate and sustain are synonyms defined as:

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

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

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