There are a lot of similarities between the Nano and the Micro. The Micro was released in 2012 while the Nano was released in 2008. The Nano features 14 digital I/O pins, 8 analog input pins and 6 PWM output pins. With those specifications, you may think that you should use the Micro board over the Nano however if you look at most online retailers like Amazon or eBay you can find the Nano for about half the price of the Micro.
You will also find that the Nano is easier to obtain than the Micro because there are so many generic Nano boards. We will also be using the Nano for some of the projects in this book.