1. What are the differences between the iPing app and your iPerfectPutt app?
The iPing is more of a clubfitting app which basically measures 2 things : clubface rotation during the swing and tempo.
The clubface angle at impact is calculated as well as a qualitative measure of your stroke type (3 types depending on how much the face rotates as you swing).
The tempo is measured as a ratio between backswing and forward swing. They also measure your consistency with these elements over a few putts.
The iPerfectPutt app is designed to help you sink putts and analyzes your stroke based on line and weight. In order to hit a perfect putt, you need to hit the ball on the right line (correct swing plane, clubface orientation and centered hits on the clubface) and with the right weight (maximum backswing angle and tempo), regardless of your stroke type.
The iPerfectPutt app analyzes your stroke relative to a perfect reference stroke, for a given line and weight by measuring 5 elements of the putting stroke (6 if you add detecting off-center hits) : clubface rotation, tempo, swing plane, putt weight and clubhead speed. So, the app can help you on a putting green, to figure out why you are missing a specific putt (straight, breaking or lag).
The clubface rotation angle is not only calculated at impact, but for every position of the putting stroke and you can view these results, in detail, 2 different ways: on a graph or watch a video simulation of your stroke. There is also a feature that enables you to get auditory (sounds) feedback in real time during the swing telling you if you are rotating too much (open or closed) in comparison with a reference stroke which can be a pendulum (perfect stroke) or one of your saved strokes.
The swing plane deviation is presented the same way as the clubface rotation described above, for every position of the putting stroke. It measures by how much your swing plane is deviating, either inside or outside, from a reference stroke (either a perfect pendulum stroke or one of your saved strokes). You can also receive auditory feedback during the swing telling you if you are swinging inside or outside the reference swing plane.
The tempo is measured by downswing time and backswing time. It can also be viewed in detail on a graph or by watching a video simulation of the stroke (where you can visualize where the stroke lags behind or overtakes the reference stroke). The clubhead speed is calculated as a statistic.
Putt weight is measured by the maximum backswing angle. A bell-like sound indicates, while you are swinging, the position of the maximum backswing angle of the reference stroke you are trying to reproduce. This, along with the tempo, will lead to weight control.
So you will know automatically during the swing if you are within range for a given element (no sounds produced) and you can always analyze things as well by studying the graphs and watching the video simulation of your stroke after the swing.
This sums up the major differences.