PokerTracker

Is there a way to create a stat that is the differential between VPIP and PFR? Thanks

There is an existing statistic called 'PFR/VPIP' that expresses the difference as a ratio. If you want someting else then that would require a custom statistic - see this guide for the basics on custom statistics creation and this guide for a deeper walkthrough. While the latter was written for PokerTracker 3 and the user interface is different the techniques still apply to PokerTracker 4.