attest vs bear witness

attest and bear witness both are verbs.

Word	Noun	Adjective	Verb	Adverb
attest	No	No	Yes	No
bear witness	No	No	Yes	No

As verbs, bear witness is a hypernym of attest; that is, bear witness is a word with a broader meaning than attest:

attest: provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
bear witness: provide evidence for

Other hypernyms of attest include evidence, prove, show, testify.

As verbs, attest and bear witness are synonyms defined as:

Other synonyms of attest include take the stand, testify.

attest (verb)	bear witness (verb)
authenticate, affirm to be true, genuine, or correct, as in an official capacity	give testimony in a court of law
provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes	provide evidence for
give testimony in a court of law
establish or verify the usage of