title: Azure AD SPN and UPN?
body: <p>I want to understand the difference between the SPN &amp; UPN in Azure AD Context. My understanding is there are three way to establish identity in Azure AD</p>
  
  <ol>
  <li>Users Key in their username and Password to establish Identity</li>
  <li>An application using ClientId and Secret Key to establish Identity</li>
  <li>An application using ClientId and Certificate to establish Identity</li>
  </ol>
  
  <p>Is User/Password is called UPN &amp; rest two are called SPN? Also is there any other way to establish identity?</p>