The Galaxy S6 and S6 Edge have reclaimed the title of best Android smartphone for Samsung, and a big part of their appeal stems from the excellent 16-megapixel camera that they share. It turns out, however, that not every handset has the exact same camera: some phones use a Sony IMX240 imaging sensor while others are equipped with Samsung's own ISOCELL sensor. This appears to be an effort to pad out inadequate supply of whichever sensor is Samsung's first choice, and isn't determined by whether you buy an S6 or Edge variant of the phone.
When contacted by The Verge, Samsung explained that it sets stringent quality standards for the user experience of its phones and only uses components that live up to those expectations. In other words, you'll have an awesome 16-megapixel camera, no matter the particulars of the hardware inside:
"The Galaxy S6 and S6 Edge utilize camera sensors from several different vendors. Like all of the technology used in our products, they meet our strict global quality and performance standards."
Samsung declined to elaborate on how the different Sony and Samsung sensors are distributed geographically, or the specific reason for why a universal part isn't used across the entire range. SamMobile has already managed to perform a side-by-side comparison between the two Galaxy S6 camera versions, and the results seem to agree with Samsung's self-assessment. Image quality in the sample images appears to be a tie between the two sensors, with Samsung's ISOCELL showing a slight advantage with a better white balance than the Sony chip.