Both Canon 80D and Canon 750D 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 80D and 750D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 80D and Canon 750D Cameras
Canon 80D and Canon 750D have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
DxOMark Sensor Scores
Both Canon 80D and Canon 750D sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, 80D has scored 79, 8 points higher than 750D.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 80D
79
23.6 bits
13.2 Evs
1135 ISO
Canon 750D
71
22.7 bits
12.0 Evs
919 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
Canon 80D
or the
Canon 750D ,
including hyperfocal distance.