Ricoh GXR S10 24-72mm has a
10.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CCD sensor and features Smooth Imaging Engine IV processor. On the other hand, Ricoh GXR GR Lens A12 28mm has a
12.0MP APS-C (23.6 x 15.7 mm ) sized CMOS sensor and features GR Engine III processor.
Below you can see the GXR S10 24-72mm F2.5-4.4 VC and GXR GR Lens A12 28mm F2.5 sensor size comparison.
As seen above, Ricoh GXR GR Lens A12 28mm has a 8.9x Larger sensor area than Ricoh GXR S10 24-72mm. 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.