Both Panasonic S5 and Fujifilm XF10 have 24.0 MP resolution sensors but Panasonic S5's sensor is Full frame (35.6 x 23.8 mm ) and Fujifilm XF10's sensor is APS-C (23.5 x 15.7 mm ).
Since Panasonic S5's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Fujifilm XF10.
Another difference between these two cameras is that Panasonic S5'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 moire occurring in certain scenes.
Below you can see the S5 and XF10 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic S5 and Fujifilm XF10 Cameras
As seen above, Panasonic S5 has a 2.3x Larger sensor area than Fujifilm XF10. 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.