Internally: The Kvaser U100 uses a much more powerful processor compared to the Kvaser Pro and Light interfaces. Even though it is more powerful, it still consumes less power.
Externally: The USB communication is much more optimized, both in the Kvaser U100 hardware and also in the Kvaser Drivers. There is no need to do any smart “repacking and bundling” of the CAN frames as the Kvaser U100 has the capacity to handle both USB and CAN communication at the same time.