Mobile Device, Smartphone, Media Tablet

Mobile device: Small device that has build-in computing or internet capability.

Smartphone: Mobile device based on a mobile phone that includes internet capabilities & mobile apps.

Media Tablet: Mobile device that's usually larger than a smartphone that is used to display multimedia content. 

Here's a video explaining the difference between smartphones and mobile phones: https://www.youtube.com/watch?v=0rJ8GdKbd5U