vouch vs testify

vouch and testify both are verbs.

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

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

Other hypernyms of vouch include attest, bear witness, take the stand.

vouch (verb)	testify (verb)
give supporting evidence	give testimony in a court of law
summon (a vouchee) into court to warrant or defend a title	provide evidence for
give personal assurance; guarantee
give surety or assume responsibility