The Arduino Pro Mini is a microcontroller board based on the ATmega328P. It has two voltage which is 5v and 3v3 ( also as 3.3v). When you want to talk about the digital pinouts s that helps in programming the 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog

The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard oneArduino NanoThe classic