Canon A2200 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features DIGIC 4 with iSAPS technology processor. On the other hand, Canon IXUS 165 has a
20.0MP 1/2.3' (6.17 x 4.55 mm ) sized CCD sensor and features DIGIC 4+ processor.
Canon IXUS 165's sensor provides 6MP more than Canon A2200'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 A2200 and IXUS 165 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon A2200 and Canon IXUS 165 Cameras
Canon A2200 and Canon IXUS 165 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Canon A2200 has 42% larger pixel area compared to Canon IXUS 165, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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
Canon A2200
or the
Canon IXUS 165 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.3-inch versus 1/2.3' ),
so compare them at the same framing rather than the same focal length.
Put the same focal length on the smaller sensor and it will show less depth of
field, not more, because it also crops tighter. The calculator shows the
full frame equivalent focal length for each body so you can match the framing.