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. On the other hand, Olympus E-PL7 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VII processor.
Below you can see the GXR GR Lens A12 28mm F2.5 and E-PL7 sensor size comparison.
As seen above, Ricoh GXR GR Lens A12 28mm has a 1.6x Larger sensor area than Olympus E-PL7. 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.