Leica X1 has a
12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor . On the other hand, Leica X Vario has a
16.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor .
Below you can see the X1 and X Vario sensor size comparison.
Leica X1 and Leica X Vario have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Leica X1 has 32% larger pixel area compared to Leica X Vario, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.