3. As for display size and display resolution, the Nexus is 5.7", iPhone is 5.5". The Nexus 6P has a 7 percent bigger screen than latter. But the iPhone 6S Plus has one of the best phone displays we've seen, with its combination of maximum brightness, white balance, color accuracy and good (though not the best) pixel density.
4. Last but not the least: let me check both of software. The Nexus launches with stock Android 6.0 Marshmallow, while the iPhone runs iOS 9. Of course, now you can upgrade your iPhone 6S Plus.