Casio EX-ZS5 has a
14.0MP 1/2.3-inch (6.16 x 4.62 mm ) sized CCD sensor and features Exilim Engine 5.0 processor. On the other hand, Sony W810 has a
20.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Sony W810's sensor provides 6MP more than Casio EX-ZS5's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the EX-ZS5 and W810 sensor size comparison.
Sensor Size and Resolution Comparison image of Casio EX-ZS5 and Sony W810 Cameras
Casio EX-ZS5 and Sony W810 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Casio EX-ZS5
or the
Sony W810 ,
including hyperfocal distance.