Ricoh CX4 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Smooth Imaging Engine IV processor. On the other hand, Ricoh CX2 has a
9.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Smooth Imaging Engine IV processor.
Below you can see the CX4 and CX2 sensor size comparison.
Ricoh CX4 and Ricoh CX2 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Ricoh CX2 has 11% larger pixel area (3.13µm2 vs 2.81µm2) compared to Ricoh CX4, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.