Both Nikon S8200 and Sony NEX-5T have 16.0 MP resolution sensors but Nikon S8200'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 Nikon S8200.
Below you can see the S8200 and NEX-5T sensor size comparison.
As seen above, Sony NEX-5T has a 13.0x Larger sensor area than Nikon S8200. 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.