Both Canon 400D and Sony S930 have 10.0 MP resolution sensors but Canon 400D's sensor is APS-C (22.2 x 14.8 mm ) and Sony S930's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Canon 400D'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 Sony S930.
Below you can see the 400D and S930 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 400D and Sony S930 Cameras
As seen above, Canon 400D has a 11.7x Larger sensor area than Sony S930. 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.