cisco dpc3941b mac filtering

In the dpc3941b MAC filter settings what is the difference between "Allow All" and "Allow"?

"Allow All" means do not use the MAC address list at all to deny access.  It's just another way of saying disable MAC address filtering.

Also, are there two different MAC lists, one for Allow and one for Deny?

No, there is only one MAC address list.  Whether this list is used to allow only the devices on the list to connect to the Wi-Fi or whether it is used to allow all BUT the devices on the list to connect to the WiFi depends upon the setting of "Allow" or "Deny".  Deny means deny only the devices in the list.  Allow means allow only the devices in the list.