vouch vs substantiate

vouch and substantiate both are verbs.

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

As verbs, substantiate is a hypernym of vouch; that is, substantiate is a word with a broader meaning than vouch:

Other hypernyms of vouch include affirm, confirm, corroborate, support, sustain.

vouch (verb)	substantiate (verb)
give supporting evidence	solidify, firm, or strengthen
summon (a vouchee) into court to warrant or defend a title	establish or strengthen as with new evidence or facts
give personal assurance; guarantee	make real or concrete; give reality or substance to
give surety or assume responsibility	represent in bodily form