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 A2500 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the A2200 and A2500 sensor size comparison.
Canon A2200 and Canon A2500 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 14% larger pixel area compared to Canon A2500, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.