Then there is the whole pentile thing which may or may not apply to the iPhone. I have a Galaxy Tab S 8.4 which has a 359 DPI pentile display. But the actual effective DPI is 33% lower, and there is a strange graininess to the display. It is an inferior display to the iPad in terms of resolution and usability.
Not really sure what to make of this news..
There are OLEDs without pentile, thats mostly a samsung thing to boost specs.