Fujifilm S1 has a 16.0MP 1/2.3" (6.17 x 4.55 mm ) sized CMOS sensor . On the other hand, Sony RX10 has a 20.0MP 1" (13.2 x 8.8 mm ) sized BSI-CMOS sensor and features Bionz X processor.
Below you can see the S1 and RX10 sensor size comparison.
As seen above, Sony RX10 has a 4.1x Larger sensor area than Fujifilm 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.