A DevKit Theme is a Genesis Child Theme that started off as the latest Genesis Sample Theme and then was customized using the Genesis DevKit Plugin. This means that this theme not only includes a unique set of DevKit files, but more importantly this means that it can be continually customized by DevKit using the hundreds of point-n-click design options and powerful custom coding tools.
It’s also worth noting that these themes are completely independent of the DevKit Plugin itself. This means that you can install it on a WordPress powered site that doesn’t have Genesis DevKit installed on. But even more awesome is the fact that at any time you can install and activate Genesis DevKit on that site and then use it to customize that theme using all of the DevKit options and DEV tools!
Also note that a DevKit Theme is created and customized using all of the WordPress and Genesis best practices in mind. This helps keep these themes fast, efficient, and rock solid reliable!