The main difference is that the Vega offers middle eastern styles in addition to the internal styles found in the XD9 and there are additional middle eastern sounds in the VEGA.
Also, the Vega has dedicated quarter tone tunning buttons for one complete octave. Because of these extra buttons and for the way middle eastern musicians want there keyboards to work, there are also some different buttons on the VEGA.
The Vega has a single pitch bend/ modulation controller where the XD0 has a Modulation Wheel and a Pitch Bend Wheel.
George Kaye
Kaye's Music Scene
Reseda, California