Authentication vs. Non-Repudation

in Security+
I am taking the Security+ Wednsday for the second time, and I am going over some notes and was wondering that wouldn't Authentication provide for Non-Repudation since you already trust who the message is coming from ?
Comments
Authentication verifies who you are (User-ID) while Non-Repudiation verifies what you did (e.g Sending a message).
Another difference is that Authentication is mostly done through a central instance (like Radius, LDAP, etc.) and Non-Repudiation can be verified by anyone (using the available public key).
Make sure you get all the terms, they are important ! See my review in the Sec+ section.
Regards,
Lordy
Goal for 2014: RHCA
Goal for 2015: CCDP