The Cable for Ardunio Nano (USB 2.0 A to USB 2.0 Mini B) 30cm Connects speed-critical devices, such as smartphones and peripherals that require a Mini-B connection to your computer.
The Ardunio Mega 2560 is a microcontroller board based on the ATmega2560
The Ardunio Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Ardunio Nano 3.x) or ATmega168 (Ardunio Nano 2.x).
The Arduino UNO Rev.3 board is a microcontroller board based on the ATmega328 (data sheet)