I sent a email and this was the reply I was sent.
"Our VPI’s are a concentrated form of our Soft Plastic Paint line (SPP). Our SPP line is spray ready out of the can and is tailored for that application. The VPI line will give the more advanced Lure Maker a few more options. It is more effective for dipping tails, dotting applications, or if you are doing some brush applications. But it can also be thinned back and works just the same as the SPP line for spray applications. It is available in quarts and gallons for users who do higher volume and need more options. We are working on getting images on the web at this time."