ArbotiX-M vs ArbotiX

Robocontroller Analog Input Ports with 3-pin Connector Digital I/O Ports with 3-pin Connector PWM Ports 16Mhz ATEMGA644p Processor Dual TTL Serial Ports 3 Three-pin DYNAMIXEL Srvo Ports ISP Programming Port FTDI Serial Communications Port XBee Socket DC Screw Terminal DC Barrel Jack Seperate Power Bus for Hobby Servos Dedicated I2C Port 2x DC Brushless Moto Controllers
ArbotiX-M 8 20 6
ArbotiX 8 8 2