Authenticate vs Vendor - What's the difference?

As a verb authenticate

is to render authentic; to give authority to, by the proof, attestation, or formalities required by law, or sufficient to entitle to credit.

a person or a company that vends or sells.

(Webster 1913)

(en-verb)

To render authentic; to give authority to, by the proof, attestation, or formalities required by law, or sufficient to entitle to credit.

To prove authentic; to determine as real and true; as, to authenticate a portrait.

(wikipedia vendor)

* vender

A person or a company that vends or sells.

* merchant * seller