Both Canon G16 and Fujifilm X10 have 12.0 MP resolution sensors but Canon G16's sensor is 1/1.7" (7.44 x 5.58 mm ) and Fujifilm X10's sensor is 2/3" (8.8 x 6.6 mm ).
Since Fujifilm X10'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 Canon G16.
Below you can see the G16 and X10 sensor size comparison.
As seen above, Fujifilm X10 has a 1.4x Larger sensor area than Canon G16. 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.
DxOMark Sensor Scores
Both Canon G16 and Fujifilm X10 sensors have been tested by DxoMark. DxoMark scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Of the two cameras that we are comparing, G16 has scored 54, 4 points higher than X10.