The Arduino Nano and Uno are equipped with very similar processors (the chip that essentially serves as the brain of the board). The Nano features an ATmega328, while the Uno sports an ATmega328P.

The Arduino Team presented some new products at Maker Faire this weekend. It’s a significant update. The Arduino UNO and Arduino Mega 2560 update the Duemilanove and Mega respectively. They n… ...

The board is built around an ATtiny3217 and has almost all of the Nano’s features, like a USB port, reset button, built-in LEDs, 5 V regulator, and preloaded bootloader.

It's of course backwards compatible with existing Arduino add-ons, but sets itself apart with a new USB controller with lower latency and driver-free operation on Mac and Linux.