Here’s a no-PCB Arduino ... and an LED. This is modeled after the Lilypad hardware, and fits nicely on top of the plastic case of the microcontroller, allowing it to be used in a breadboard ...

You'll also notice that the Nano's pins are male since it's designed to be placed on a breadboard. Conversely, the Uno's pins are female. Both the Arduino Nano and Uno can be powered via their ...