
iFixit is in the process of taking apart the brand new iPhone 6s. While the internals aren't arranged too differently from the iPhone 6, there are some major visual differences worth noting. These include the new Taptic Engine, a smaller battery and the 3D Touch display.

The most instantly recognizable difference is the smaller battery. While Apple's 3D Touch video previously confirmed that the iPhone 6s would carry a 1715 mAh batter, which is smaller than the iPhone 6's 1810 mAh battery, iFixit's teardown provides further confirmation.
Another major visual difference comes in the presence of the new Taptic Engine, which takes up a large amount of space below the battery and is likely to account for the smaller size of the iPhone 6s' battery. iFixit blasted the Taptic Engine with x-rays, providing a peek into the oscillating mechanism under the aluminum shell.

iFixit's iPhone 6s teardown is ongoing and this post will be updated if significant discoveries are made.
Article Link: iPhone 6s Teardown: 1715 mAh Battery, Taptic Engine X-Ray, 3D Touch Display