The entire design of the phone still remains a mystery for now. Instead the photos show us the chassis of the handset, or more specifically its back portion minus the display. So far based on what we can tell, the design of the phone looks similar to the current iPhone 6/6 Plus models, which is kind of expected.
However internally there appears to be some changes, such as the different placements of the screws that hints that Apple might have moved some internal components around. According to the person who got their hands on the component, they claim that this material feels different compared to the previous iPhone.
This could be alluding to the rumor that the next-gen iPhone could be made of stronger aluminum. In any case take it with a grain of salt for now, but for the most part we don’t expect the iPhone 6s/6s Plus to be too different in appearances.