The Arduino, Raspberry Pi, and ODROID may look quite similar – they’re all cute little circuit boards with some chips and pins on them – but they are in fact very different devices. The Arduino is in fact a micro-controller; not a mini-computer. A micro-controller is just a small part of what makes a computer, and only provides a subset of the functionality of the Rapsberry Pi or ODROID.
Although the Arduino can be programmed with small C-like applications, it cannot run a full scale “operating system” and certainly won’t be replacing your media-center anytime soon. The Raspberry Pi or ODROID on the other hand, are computers. If you’re reading this site, I’m just going to assume you know what that means.