Panasonic SZ1 has a
16.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Epson R-D1x has a
6.0MP APS-C (23.7 x 15.6 mm ) sized CCD sensor .
Panasonic SZ1's sensor provides 10MP more than Epson R-D1x'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 SZ1 and R-D1x sensor size comparison.
As seen above, Epson R-D1x has a 13.3x Larger sensor area than Panasonic SZ1. 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.