Panasonic FX48 has a 12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Sony A850 has a 25.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor and features Bionz processor.
Sony A850's sensor provides 13MP more than Panasonic FX48'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 FX48 and A850 sensor size comparison.
![Panasonic FX48 vs Sony A850 Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Panasonic FX48 and Sony A850 Cameras
As seen above, Sony A850 has a 31.1x Larger sensor area than Panasonic FX48. 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.