Fujifilm SL300 has a 14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony RX10 III has a 20.0MP 1-inch (13.2 x 8.8 mm ) sized BSI-CMOS sensor and features Bionz X processor.
Sony RX10 III's sensor provides 6MP more than Fujifilm SL300'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 SL300 and RX10 III sensor size comparison.
![Fujifilm SL300 vs Sony RX10 III Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Fujifilm SL300 and Sony RX10 III Cameras
As seen above, Sony RX10 III has a 4.1x Larger sensor area than Fujifilm SL300. 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.