Some rumors suggest Apple is aiming to make the iPhone 7 thinner, perhaps through the removal of the 3.5mm headphone jack and the implementation of a thinner Lightning port, but other rumors suggest the iPhone 7 and 7 Plus will have a body that is the same thickness as the iPhone 6s.
With no headphone jack, wired headphones will connect to the iPhone 7 using its Lightning port and Bluetooth headphones will connect wirelessly. Apple is rumored to be working on Lightning-equipped EarPods to sell alongside the iPhone 7.
Blueprints and an image of a device said to be the iPhone 7 Plus have surfaced depicting a Smart Connector on the back of the shell, suggesting that is another potential feature, but it is not yet clear what it would be used for and other rumors have said it will not be included. If the Smart Connector rumors are accurate, it will be a feature limited to the larger-screened model.
Internal specs for the iPhone 7 aren't yet known, but we can speculate Apple will continue on its path of introducing more powerful, efficient devices with each design iteration. The iPhone 7 and iPhone 7 Plus are expected to include next-generation A10 processors manufactured by TSMC.
There are rumored to be some distinguishing features between the iPhone 7 and the larger-screened iPhone 7 Plus. The iPhone 7 may ship with 2GB RAM, while the iPhone 7 Plus could include 3GB RAM, and there is said to be a different camera system in the iPhone 7 Plus that uses two cameras instead of one with 2-3x optical zoom and improved performance in low-light conditions. The iPhone 7 will likely continue to use a standard single-lens camera as multiple sources have said the dual lens camera is exclusive to the 5.5-inch iPhone.