title: Difference between "System Assigned" Identity and App Registration "Service Principal"
body: <p>Can someone help me understand the difference between the Service Principal created when I create an App Registration in AAD and the Managed Identity that gets created when I enable "System Assigned" on the Identity blade of an App Service?</p>
  
  <p>We have an App Service that we are developing that we have created an App Registration for and we have also enabled the System Assigned identity. When we go into Enterprise Applications under AAD and search for our app, it comes up with 2 entries. One for the Managed Identity and one for the Service Principal created as part of the App Registration. We are trying to understand which one we would use to give the app permissions to write to an Azure SQL DB.</p>