spooks, there are different types of printable discs. Thermal Printables= for use on Thermal printers. Inkjet Printables= for use on Inkjet Printables.
When you see "Hub-Printable", that means the hub (center of disc) is also white and is able to be printed on. If you see a disc that is printable, but doesn't say that it's hub printable, then you can only print up to the hub.
If you are just wanting white discs to write on, then I'd probably get the thermal printable media.(since you aren't going to print to them) They have a better (smoother) finish than the inkjet printables.
[b]See the attached pics: Notice the first pic is a HUB PRINTABLE disc. See how the white goes all the way up to the hole.
2nd pic is a regular printable disc (not a hub printable). See how the white only goes up to the hub and stops.[/b]