FujiFilm S2500HD has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Canon A3300 IS has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features DIGIC 4 with iSAPS technology processor.
Below you can see the S2500HD and A3300 IS sensor size comparison.
FujiFilm S2500HD and Canon A3300 IS 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 FujiFilm S2500HD has 32% larger pixel area compared to Canon A3300 IS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.