Both Olympus SP-610UZ and Sony NEX-3 have 14.0 MP resolution sensors but Olympus SP-610UZ's sensor is 1/2.3-inch (6.17 x 4.55 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 SP-610UZ.
Below you can see the SP-610UZ and NEX-3 sensor size comparison.
As seen above, Sony NEX-3 has a 13.0x Larger sensor area than Olympus SP-610UZ. 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.