Both Sony a5000 and YI M1 have 20.0 MP resolution sensors but Sony a5000's sensor is APS-C (23.2 x 15.4 mm ) and YI M1's sensor is Four Thirds (17.3 x 13 mm ).
Since Sony a5000's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to YI M1.
Below you can see the a5000 and M1 sensor size comparison.
As seen above, Sony a5000 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.