Fujifilm X-E3 has a 24.0MP APS-C (23.6 x 15.6 mm ) sized CMOS X-TRANS III sensor and features EXR Processor III processor. On the other hand, YI M1 has a 20.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Another difference between these two cameras is that Fujifilm X-E3'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 X-E3 and M1 sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm X-E3 and YI M1 Cameras
As seen above, Fujifilm X-E3 has a 1.6x Larger sensor area than YI M1. 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.