Pentax X90 has a 12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Prime processor. On the other hand, Panasonic FZ1000 II has a 20.0MP 1-inch (13.2 x 8.8 mm ) sized BSI-CMOS sensor and features Venus Engine processor.
Panasonic FZ1000 II's sensor provides 8MP more than Pentax X90'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 X90 and FZ1000 II sensor size comparison.
![Pentax X90 vs Panasonic FZ1000 II Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Pentax X90 and Panasonic FZ1000 II Cameras
As seen above, Panasonic FZ1000 II has a 4.2x Larger sensor area than Pentax X90. 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.