Panasonic S5 II X has a 24.0MP Full frame (35.6 x 23.8 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Sony FX30 has a 26.0MP APS-C (23.5 x 15.6 mm ) sized BSI-CMOS sensor and features Bionz XR processor.
Another difference between these two cameras is that Panasonic S5 II X's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the S5 Mark II X and FX30 sensor size comparison.
As seen above, Panasonic S5 II X has a 2.3x Larger sensor area than Sony FX30. 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.