Leica M9-P has a
18.0MP Full frame (36 x 24 mm ) sized CCD sensor . On the other hand, Fujifilm X-Pro1 has a
16.0MP APS-C (23.6 x 15.6 mm ) sized CMOS X-TRANS I sensor and features EXR Pro processor.
Another similarity between these two cameras is that both Fujifilm X-Pro1 and Leica M9-P sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the M9-P and X-Pro1 sensor size comparison.
As seen above, Leica M9-P has a 2.3x Larger sensor area than Fujifilm X-Pro1. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.