iFixit have been tearing down I devices for a long time and the new iPhones are no different, the guys there have just published their findings. 

During the tear down they document everything and some of the things they found is that “The iPhone 7 Plus is a hair larger than its predecessor (158.2 x 77.9 x 7.3 mm vs. 158.1 x 77.8 x 7.1 mm), and it’s stamped with a new model number: A1785. The adhesive strip sealing the 7 Plus is considerably stronger than the strip we found in its predecessor.”

The full process is fascinating and the full findings can be found here