The camera on the windshield is the one that handles such features as Lane Keep Assist and Lane Departure Warning.
The mirror is a bit trickier, since it depends on whether or not the vehicle originally had the regular mirror or the Rear Camera Mirror feature.
Info on the Rear Camera Mirror here:
https://gmauthority.com/blog/gm/general-motors-technology/gm-safety-technology/gm-active-safety-technology/gm-rear-camera-mirror/
