Both Olympus 5010 and Sony NEX-3 have 14.0 MP resolution sensors but Olympus 5010's sensor is 1/2.3-inch (6.08 x 4.56 mm ) and Sony NEX-3's sensor is APS-C (23.4 x 15.6 mm ).
Since Sony NEX-3'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 Olympus 5010.
Below you can see the 5010 and NEX-3 sensor size comparison.
As seen above, Sony NEX-3 has a 13.2x Larger sensor area than Olympus 5010. 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.