Both Canon SL2 and Nikon D5200 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 SL2 and D5200 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon SL2 and Nikon D5200 Cameras
As seen above, Nikon D5200 has a 1.1x Larger sensor area than Canon SL2. 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.
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. Canon SL2 and Nikon D5200 sensors have been tested by DxO and the results show that D5200 has a better overall score of 84, 5 points higher compared to SL2's score of 79.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon SL2
79
23.6 bits
13.4 Evs
1041 ISO
Nikon D5200
84
24.2 bits
13.9 Evs
1284 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 SL2
or the
Nikon D5200 ,
including hyperfocal distance.