Canon A1200 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features DIGIC 4 with iSAPS technology processor. On the other hand, Sony NEX-3 has a
14.0MP APS-C (23.4 x 15.6 mm ) sized CMOS sensor and features Bionz processor.
Below you can see the A1200 and NEX-3 sensor size comparison.
As seen above, Sony NEX-3 has a 13.0x Larger sensor area than Canon A1200. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.