Authenticated users are those who are logged into the site.
Identified users are those who have registered and agreed to your current Terms and Conditions, which includes tracking. The tracking is done by means of a cookie, this means that Affino identifies them whether they are logged in or not, so long as the cookie is still saved by the browser.
On the other hand, users who enter the site from a Message Campaign, even though logged out and without a tracking cookie, are identified by Affino. This is because every link on a message has the contacts User ID, Affino knows to who the message was sent and which contact clicked on a link.
Note: Non Members and Mailing List contacts are still "users" and have User ID codes