testify vs vouch

testify and vouch both are verbs.

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

As verbs, vouch is a hyponym of testify; that is, vouch is a word with a more specific, narrower meaning than testify:

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