Canon SX240 HS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Digic 5 processor. On the other hand, Nikon S9300 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Below you can see the SX240 HS and S9300 sensor size comparison.
Canon SX240 HS and Nikon S9300 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 SX240 HS has 32% larger pixel area compared to Nikon S9300, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.