1x front USB 2.0 port.
Smart Device V2 which includes:
3x Fan channels with Max 10W per channel output*
2x RGB LED port support up to 4x HUE 2 addressable LED strips or 5x Aer RGB or Aer RGB 2 fans
Built-in noise detection module
Aside from that, the two cases are identical. If you don't need a front USB 2.0 or RGB (I can't wait until that fad dies off), then I see no reason to spend the extra $30 for the H510i
The so called Smart Device V2 is a big joke, a piece of junk. Do not pay anything extra for it. You do the settings it provide faster and more simple then when using that so called "smart device!"