Driving: Allows the player to create his own shot without a good pass from a teammate. Better driving creates shots more often and creates better shots on average.
Inside Shot: A better inside shooter will make more two-point baskets.
Inside Shot can be anything close to the basket. Or at least that's how I see it. I like to think of IS affecting not only back-to-basket shots, but fadeaway, turnaround and baseline jumpers, drives, putbacks, etc. It may have less of an effect on some shots compared to others.