How much better is the picture quality of Canon III than that of Canon III?

Under the same technical conditions, the larger the size of the imaging unit, the better the imaging quality.

As for the number of pixels per inch, the resolution will be better if the imaging unit of the same size has a high number of pixels per inch. But if the unit pixel area is large, the tolerance and noise performance will be better.

There are many factors that determine the image quality, such as resolution, tolerance, color representation, noise representation and so on. High pixels have the advantages of high pixels and low pixels have the advantages of low pixels. If the imaging units are the same size, the image quality is basically the same regardless of whether the pixels are high or low.