UAL makes the following distinction between authentication type methods:

• Impersonating authentication types will make requests on behalf of the user that is currently logged in. This includes OAuth and Trusted Apps authentication.
• Non-impersonating authentication types always use a pre-configured user when making a request. This includes basic HTTP authentication.

To determine which is the right authentication type to configure, you should refer to the documentation for the feature that is using UAL.

In general, impersonating authentication types are a good fit for the following:

• A feature with functionality that displays information that is only visible to the logged in user from a remote application.
• A feature with functionality where actions are performed on behalf of the current user in the remote server.

In general, non-impersonating authentication types are a good fit for the following:

• A feature that relies on having a certain permission at the remote application, regardless of whether the current logged-in user has the permission.