title: AddIdentity vs AddIdentityCore
body: <p>In ASP.NET Core, you can add various services for identification: <code>AddDefaultIdentity</code>, <code>AddIdentity</code> and <code>AddIdentityCore</code>.</p>
  
  <p>What's the difference between <code>AddIdentity</code> and <code>AddIdentityCore</code>?</p>