CAN bus (Controller Area Network) is a vehicle bus standard that allows devices such as motor controllers, sensors, and other ECU’s (electronic control unit) to communicate with each other. CAN bus acts as the nervous system of the vehicle.
CANopen is a high-level protocol originally designed for motion-oriented machine control systems. While CANopen was originally designed for motion control it’s now used in a wide variety of applications and every vehicle today is equipped with CAN bus.