The Super Grip uses an advanced copolymer coating that provides a higher friction surface on the thumb piece (it is similar to a vinyl coating). This provides a grippier propulsion surface for your thumb. For users who want both the ergonomic benefits of the Natural-Fit along with a grippier propulsion surface, the Super Grip will be the better choice for you.
The Standard Grip uses a powder coat on the thumb piece that provides a low friction surface to go along with the smooth braking surface on the oval. For those users interested in the ergonomic features of the Natural-Fit but who do not like high friction surfaces, then the standard grip may be your best choice for you.