Fujifilm X100 has a
12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor and features EXR processor. On the other hand, Leica D-Lux Typ 109 has a
13.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Another difference between these two cameras is that Fujifilm X100's sensor lacks anti-alias (Low-Pass) filter. 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 X100 and D-Lux Typ 109 sensor size comparison.
As seen above, Fujifilm X100 has a 1.7x Larger sensor area than Leica D-Lux Typ 109. 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.