Ricoh CX3 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, Olympus E-M10 II has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VII processor.
Olympus E-M10 II's sensor provides 6MP more than Ricoh CX3's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the CX3 and E-M10 II sensor size comparison.
As seen above, Olympus E-M10 II has a 8.0x Larger sensor area than Ricoh CX3. 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.