The main differences between the NEO 3 Pro and NEO 3 is as below:
NEO 3 Pro adopts the STM32F412 processor, RM3100 Compass, MS5611 Barometer. The protocal is UAVCAN.
NEO 3 adopts IST8310 compass, and the protocal is UART/IO/12C.
CUAV New NEO 3 GNSS U-blox M9N GPS Module is compatible with PIXHAWK flight controllers. It supports Beidou, Galileo, Glonas and GPS receive at teh same time, and the horizontal posioning accuracy is up to 0.7M. The CUAV NEO 3 GPS module also integraged with safety switch, buzzer, RGB light.