What's the difference between basic and premium?

We offer two types of SketchBoxes - Basic and Premium.  Our two boxes contain the same types of supplies, just different versions.  For example one month we shipped paint markers. The basic box had Uni paint markers, and the premium box had Krink paint markers (valued at almost $9 each in stores). The premium box will contain a higher quality version of the same supplies found in the basic box.