Both Canon R7 and Sony A7 IV have 33.0 MP resolution sensors but Canon R7's sensor is APS-C (22.2 x 14.8 mm ) and Sony A7 IV's sensor is Full frame (35.8 x 23.8 mm ).
Since Sony A7 IV'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 Canon R7.
One other difference between these two cameras that is worth mentioning is that Sony A7 IV's sensor doesn't have an 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 moire occurring in certain scenes.
Below you can see the R7 and A7 IV sensor size comparison.
![Canon R7 vs Sony A7 IV Sensor Size Comparison]()
Sensor Size and Resolution Comparison image of Canon R7 and Sony A7 IV Cameras
As seen above, Sony A7 IV has a 2.6x Larger sensor area than Canon R7. 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.