Canon 100D has a
18.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 5 processor. On the other hand, Canon M50 has a
24.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 8 processor.
Canon M50's sensor provides 6MP more than Canon 100D's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the 100D and M50 sensor size comparison.
Canon 100D and Canon M50 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. On the other hand, since Canon 100D has 33% larger pixel area compared to Canon M50, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.