Both Canon SX500 IS and Sony NEX-5T have 16.0 MP resolution sensors but Canon SX500 IS's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Sony NEX-5T's sensor is APS-C (23.4 x 15.6 mm ).
Since Sony NEX-5T'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 SX500 IS.
Below you can see the SX500 IS and NEX-5T sensor size comparison.
As seen above, Sony NEX-5T has a 13.0x Larger sensor area than Canon SX500 IS. 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.