Now according to a post on Wylsa (via Ben Geskin; via 9to5Mac), alleged renders of the three iPhones have surfaced, as you can see in the image above. These renders are allegedly based on schematics on the 6.1-inch and 6.5-inch iPhones. The 5.8-inch iPhone already exists via the iPhone X so we roughly know what that looks like already.
https://twitter.com/VenyaGeskin1/status/1002598536415006726
That being said assuming these renders are accurate, the difference between all the iPhones appear to be minimal save for the obvious difference in size. However with rumors claiming that the 6.1-inch iPhone will be the more affordable model that uses an LCD display, it’s not surprising that Apple could also be further reducing costs by only giving it one camera as opposed to two.
Other than that, additional renders have also revealed that all three iPhones will use a fullscreen display with a notch, suggesting that while the 6.1-inch model could be the “cheaper” model, it could come with a TrueDepth camera system that would facilitate Face ID.