Is there any difference between road and mtb discs? I'm trying to find which discs should be used with a 105 hydro groupset but I can´t find anything. 

When I search for 105 dic brakes I'm always redirected to the calipers and not the disc it self, or just articles rim brakes vs disc brakes...

The only thing I've found which I think could be specially for road use and looks a little bit more aerodynamic than other disks are the RT800 which should correspond to ultegra.

Why aren't the discs included in the groupset? It is like buying rim brakes without brake pads.
The specific word you need is 'rotor'. If you search for 'Shimano 105 disc brakes' you tend to get the calipers rather than the rotor (which is confusingly actually the 'disc' part).

The latest 105 series rotor part name is SM-RT70. See the Shimano 105 series page. 

There will be other rotors that are compatible with 105 calipers, in case you need a 6-bolt rather than a center lock version.

Calipers don't come with rotors because different sizes are required for different applications or preferences.