What's differents between flight controller pixhawk 1&2 and 3 pro

On this article http://www.rcdronegood.com/flight-controller-board-comparison/ many famous flight controllers were recommended by a pilot, like RMRC,Crazepony F3,MultiWii, also include Pixhawk 2. I know Pixhawk is good for autonomous flying. My questions is What’s differents between pixhawk 1&2 and 3 pro flight controller? What about all-in-One module?

Pixhawk 1 is the legacy Pixhawk, released and supported by 3DR in the past. Pixhawk 2 is an evolution based on what was released on the Solo drone, supported by ProfiCNC and Hex. Pixhawx 3 Pro is a third evolution, designed and supported by Drotek. The All-in-One module contains a USB extension and an external LED in order to facilitate the access to the autopilot. Feel free to look at the specifications on the documentation and come back of you have more questions.