Sony A6500 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz X processor. On the other hand, Fujifilm X-Pro3 has a
26.0MP APS-C (23.5 x 15.6 mm ) sized BSI-CMOS sensor and features X-Processor 4 processor.
One other difference between these two cameras that is worth mentioning is that Fujifilm X-Pro3's sensor doesn't have an 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 A6500 and X-Pro3 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A6500 and Fujifilm X-Pro3 Cameras
Sony A6500 and Fujifilm X-Pro3 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony A6500 has 8% larger pixel area compared to Fujifilm X-Pro3, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sony A6500
or the
Fujifilm X-Pro3 ,
including hyperfocal distance.