Inkjet hub printable describes a specific type of CD and/or DVD. A printable disc is a disc with a special lining on one side to allow printing on that side of the disc.
Printable discs offer a unique advantage over standard discs. Recordable CDs and DVDs often require some type of labeling once they've been recorded on. The lining on printable discs allows them to be printed on or written on by hand without damaging the disc.
The difference between a printable disc and a hub printable disc has to do with the total printable space on the disc. Hub printable discs are lined closer to the center hole than basic discs, allowing almost the entire surface to be printed on.
Inkjet refers to a specific printing process that involves spraying ionized ink droplets in various patterns on a printable surface. An inkjet printable disc is a disc that can be printed on using this technology.