Nikon S9500 has a
18.0MP 1/2.3-inch (6.16 x 4.62 mm ) sized BSI-CMOS sensor . On the other hand, Nikon S9100 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Expeed C2 processor.
Nikon S9500's sensor provides 6MP more than Nikon S9100'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 S9500 and S9100 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon S9500 and Nikon S9100 Cameras
Nikon S9500 and Nikon S9100 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
Nikon S9500
or the
Nikon S9100 ,
including hyperfocal distance.