The Nexus 5 has a 5″ screen. The iPhone 6 has a 4,7″ screen. So you can see more stuff on the Nexus right? Wrong.
If you’re comparing iOS and Android screen sizes, you might need to compare the usable screen space instead of just the physical screen size.
Let’s define ‘usable’: On most modern Android devices, the lower edge of the screen is occupied by virtual on-screen keys. So you effectively have less space on which you can display content.
On the plus side, it also means that the Nexus 5 can fit a larger 5″ screen, while the slightly larger iPhone 6 can only accommodate a 4,7″ screen, since it needs a spot for the physical home button.
However, as you can see in this photo, the 4,7” iPhone 6 screen appears bigger and has more space for application content and UI, despite being 0,3” smaller than the Nexus 5:
So what does this all boil down to? Basically a 4,7” Android phone can be physically smaller than an iPhone with an equivalent screen, but you’ll sacrifice some of that screen for semi-permanent UI elements. (And yes, I’m aware that the virtual keys will hide in full-screen modes such as games or video playback, but for most apps they’re always visible).
So the 5” Nexus 5 has roughly 4,65” of usable screen space, just slightly less than the 4,7” iPhone 6. Or to put it differently, that’s why the iPhone 6 seems larger than an Android device with a ‘larger’ screen.