Both house the same 12.3 - megapixel Sony MX377 camera sensor on the back, which has large pixels (1.55 - microns) allowing it to makes the most of the light entering the lens, and both have a speedy laser autofocus system too.
Here's the last big difference the Plus adds over the G4 standard: its rear camera is not only more resolute, at 16 - megapixels (not 13MP), but offers a laser autofocussystem for enhanced low - light focusing too.