From the Storm Bowling site and their glossary:
The difference of the radius of gyration of a bowling balls X axis (the weight block vertical) compared to the radius of gyration of the same balls Y or Z axis (the weight block horizontal). Differential is an indicator of a bowling balls track flare potential. Bowling balls with lower differentials are more stable, therefore generating less track flare potential. Bowling balls with higher differentials are unstable, therefore generating a much larger track flare potential. Also, differential is a guide to the internal versatility of a ball. It can indicate just how much of a length adjustment can be made through drilling. Balls with lower differential will allow only modest length adjustments whereas balls with higher differential may translate into a length window of up to 5-times that of low differential balls.
RG:
Measured in inches, radius of gyration is the distance from the axis of rotation at which the total mass of a body might be concentrated without changing its moment of inertia.
From their Byte to Sync comparison:
G2+ Core has a higher RG and lower differential than the original G2. This modification creates a later transition and more emphasis on the backend, especially for crankers and tweeners. You’ll find that the Byte perfectly complements the Sync by providing a later break point and more entry angle.
Thus, higher RG means it revs up later, later transition, later break point, etc. Lower RG means revs up quicker, earlier transition and earlier break point...
I should have said early revs/later revs in earlier post, but...
