What is the difference in setup between the generic CDMA modems and CDMA modems preconfigured for specific wireless providers (i.e. Sprint and Verizon)?

The Sprint and Verizon models are both based on the generic models. A difference between the provisioned models and the generic models is that each carrier may have some configuration commands that are specific to that carrier. This would mean that they may have different firmware versions (which Sprint and Verizon do). The models that are already configured will also have a preconfigured PRI and PRL file loaded into them that will be specific to the carrier.

The generic models will not have anything loaded except for the main firmware file and generic PRI and PRL files. To make a generic model work on a specific carrier's network you would have to configure the modem with settings to match the carrier's network settings and load their PRL file to the modem. Settings in the PRI file can be settings such as phone numbers, channel settings, roaming settings, etc. Firmware changes will probably not be necessary unless something was needed to get approval from the carrier.