Difference between non-authenticated and pre-authenticated application assessment?

Prior to testing it's important to determine what parts of the application require authentication and authorization. Security testing should approach the application from both a non-auth and pre-auth perspective. The goal of the non-authenticated assessment is to identify any security risks which are openly exposed by the application. The authenticated assessment is to identify the security risks once a valid user logs in. For an authenticated assessment ensure that the project team provides credentials in advance.