This might be a stupid question but I recently bought the XBee 900HP Pro (XKB9-DMT-UHP) and was wondering the difference between the various firmwares available for it in XCTU and the difference between S3B Pro.
If you are referring to the XBP9B-XC and the others for the 900 HP, the XC modem type loads on the old 900 MHz XStream code onto the module. This allows the radio to act and communicate with the now discontinued 9XStream products (X09-009 and X09-019).
The XBP9B-DP and XBP9B-DM options offer the most current options such as ADC, DIO, API mode and Over the air commands where by the old XStream does not.