Hotspot Guest portal: Network access is granted without requiring any credentials. Usually, an Acceptance of User Policy (AUP) must be accepted before network access is granted.
Sponsored-Guest portal: Network access is granted by a sponsor who creates accounts for guests, and provides the guest with login credentials.
Self-Registered Guest portal: Guests can create their own account credentials, and may need sponsor approval before they are granted network access.
https://www.cisco.com/c/en/us/td/docs/security/ise/2-
4/admin_guide/b_ISE_admin_guide_24/m_ise_guest.html#ID32