Pixhawk Mini Carrier Board has the standardized DF17 connector which allows user to connect it to every version of the Cube flight controller. With smaller...
Pixhawk 2.1 or Cube autopilot is advance autopilot which is used in Professional UAVs around the world. Pixhawk 2.1 is now named as Cube Autopilot.
If you planning to build autonomous vehicle ( Aerial, Rover or Subs ) Cube aka Pixhawk 2.1 will be your first choice with ArduPilot software