Pentax Q-S1 has a
12.0MP 1/1.7" (7.44 x 5.58 mm ) sized BSI-CMOS sensor and features Q Engine processor. On the other hand, Nikon 1 J1 has a
10.0MP 1-inch (13.2 x 8.8 mm ) sized CMOS sensor .
Below you can see the Q-S1 and 1 J1 sensor size comparison.
As seen above, Nikon 1 J1 has a 2.8x Larger sensor area than Pentax Q-S1. 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.