Whenever you report on the number of unsubscribes you are going to see the number of site-wide email opt-outs, but if you run the "Unsubscribe Details Report" you will see a list of all people that clicked the unsubscribe link in an email (some of which may have only opted-out of an interest). To run this report:
  1. Email > Email Campaigns
  2. "Reports" tab
  3. Next to "Create a New Report" choose "Unsubscribe Details Report" and click "Go".
  4. Choose the email campaign you want to report on and click "Add", then click "Next" when you are done.
  5. Click on "Submit Report"
This report will show all constituents that clicked the unsubscribe link, and in the column titled "Email Subscription Change" you can see what action was taken by each constituent. The value for that column will be "Changed email interests" if the constituent only changed an email interest. If the constituent took a site-wide opt-out, you can also see the date this happened in the next column "Email Opt Out Date".