[codesci]

The 7 dropped the headphone jack, changed from physical to "virtual" home button and added water resistance so there were more structural changes than just spec and camera bumps.

I'm more curious to why they skipped 9 (or maybe that is still coming...)

[valine]

They also redesigned the antenna lines to conform to the curves of the phone. The back of the 7 looks a lot nicer than the 6s in my opinion.