What is an 'Arduino Compatible Board?
If you know Arduino's you know that it is an open sourced hardware device. This means that reference files and designs are freely provided. This means that high quality boards can be made to the exact same parts, quality, functionality, and compatibility as the official released boards. This is one of those boards 100% compatible with the Arduino IDE and built with the same parts and quality.
What is an MEGA ADK?
The Arduino MEGA ADK is a microcontroller board based on the ATmega2560 (datasheet). It has a USB host interface to connect with Android based phones, based on the MAX3421e IC. It has 54 digital input/output pins (of which 15 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button.