Fujifilm A170 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Canon SX520 HS has a
16.0MP 1/2.3' (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Digic 4+ processor.
Canon SX520 HS's sensor provides 6MP more than Fujifilm A170'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 A170 and SX520 HS sensor size comparison.
Fujifilm A170 and Canon SX520 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 Fujifilm A170 has 58% larger pixel area compared to Canon SX520 HS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.