Both Sony W330 and Sony NEX-3 have 14.0 MP resolution sensors but Sony W330'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 Sony W330.
Below you can see the W330 and NEX-3 sensor size comparison.
As seen above, Sony NEX-3 has a 13.0x Larger sensor area than Sony W330. 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.