Is the Admin role different than a role with all permissions enabled?
Yes, the user 1 is different in Drupal:


  The Drupal account created during installation (i.e. with user ID or
  UID=1) behaves differently from others. Primarily, it can bypass all
  access callbacks: it has permission to do everything by default.
  Failing to secure this account could result in potential security
  risks. Treat the UID=1 account as you would with root on Linux
  systems.


Source: https://www.drupal.org/node/947312