Both Nikon L22 and Nikon D2X have 12.0 MP resolution sensors but Nikon L22's sensor is 1/2.3-inch (6.17 x 4.55 mm ) and Nikon D2X's sensor is APS-C (23.7 x 15.7 mm ).
Since Nikon D2X'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 L22.
Below you can see the L22 and D2X sensor size comparison.
As seen above, Nikon D2X has a 13.3x Larger sensor area than Nikon L22. 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.