Canon A495 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Canon SX510 HS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Digic 4 processor.
Below you can see the A495 and SX510 HS sensor size comparison.
Canon A495 and Canon SX510 HS 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 A495 has 59% larger pixel area compared to Canon SX510 HS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.