Casio EX-100 has a
12.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CMOS sensor . On the other hand, Nikon A1000 has a
16.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Below you can see the EX-100 and A1000 sensor size comparison.
As seen above, Casio EX-100 has a 1.5x Larger sensor area than Nikon A1000. 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.