Differential Ratio, or diff. ratio, is an indicator of the level of asymmetry of the core. The differential ratio is equal to the quotient of the Intermediate differential and the Total differential. Balls with higher diff ratios have a higher degree of asymmetry.
The diff. ratio is also an indicator of how quickly the ball will respond to friction. The higher the value, the faster the response to friction. This is the reason why Asymmetric cores tend to produce more angular break points than Symmetric cores.