Canon SX10 IS has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Nikon A1000 has a
16.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Nikon A1000's sensor provides 6MP more than Canon SX10 IS'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 SX10 IS and A1000 sensor size comparison.
Canon SX10 IS and Nikon A1000 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 SX10 IS has 59% larger pixel area compared to Nikon A1000, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.