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. On the other hand, Panasonic ZS8 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine FHD processor.
Another difference between these two cameras is that Fujifilm X-Pro1'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 X-Pro1 and ZS8 sensor size comparison.
As seen above, Fujifilm X-Pro1 has a 13.3x Larger sensor area than Panasonic ZS8. 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.