I found this very useful as with my first time dealing with Apple's VPP and Config. IT manager first time tips for an Apple iOS cart ipad-ipod. As far as for an explanation, I'll do my best to explain but if anyone has a better way to put it, please chime in. If you were to buy an app through the store, that app would be locked to that machine. With vpp codes while it can be assigned to a machine, you can always pull it from that machine and assign it to a different machine. So for example, you have a few ipads with apps on them that the end user will no longer use. You can always plug the Ipad into apple config and under supervision (if I'm not mistaken) you can remove the app and always push it on to another ipad if you wanted to. It's also an easy way to keep track of your apps that you have available for you to push. You can use apple vpp to purchase 30 apps, and use apple config to push them out onto whatever ipads that need those apps. Hopefully that helps, along with the link.
