profile email notifications: can CiviCRM indicate what information has changed?
I think what you want is Logging.

In the Civi menu, go to Administer > System Settings > Misc (Undelete, PDFs, Limits, Logging, Captcha, etc.)

Enable logging, and from then on all changes to contact records will be recorded. You can view them by visiting the "Change Log" tab on the contact summary screen.