The My Zones tab lists zones you have access to (through ownership or ACL rules). The list contains links to the individual zone pages where you can manage the zone, it’s records and ACL access.
The All Zones tab is intended as a reference, it includes zones you have access to as well as all other private and shared zones in VinylDNS. If needed, you can use the contact information in the list to reach out to the owners of the zones you don’t have access to.
Note you may have access to specific records in shared zones, but you are not permitted to access those zones in this area. Those records are accessible via the DNS Changes area of the portal.