The power button on the new iPhone sits still on the side of the unit and the device looks thinner and with more curved edges than previous models.
The volume buttons on the side appear more elongate, unlike those on the iPhone 5S where they are circular in shape.
The mockup also features a round flash, which is different from the ovular True Tone setup on the previous generation.
The iPhone 6 is expected to be available in versions of 4.7 and 5.5-inch models. Both devices are expected to be announced by Apple this fall.