Both Sony A6400 and Sony A6500 have APS-C sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the A6400 and A6500 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A6400 and Sony A6500 Cameras
Sony A6400 and Sony A6500 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.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Sony A6400 and Sony A6500 sensors have been tested by DxO and the results show that A6500 has a better overall score of 85, 2 points higher compared to A6400's score of 83.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A6400
83
24.0 bits
13.6 Evs
1431 ISO
Sony A6500
85
24.5 bits
13.7 Evs
1405 ISO
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 A6400
or the
Sony A6500 ,
including hyperfocal distance.
