MX Brio has better image quality in low light or difficult lighting conditions.
MX Brio uses a Sony Starvis sensor that has 70% larger pixels than Brio 4K.
MX Brio uses AI face-based image adjustment that results in a tailored improvement of the image quality while Brio 4K uses a centered image adjustment.
The adjustments possible on the software are much more precise and complete with MX Brio. You can even adjust Tint and Vibrance, which isn’t available for Brio 4K.
The privacy shutter in MX Brio is integrated vs attachable on Brio 4K.
MX Brio does not support Windows Hello, while Brio 4K does.