Turns out, size requires compromise the iPhone 6's display appears slightly better calibrated than that of the massive 6 Plus.
So, the first and most important difference here is that the 6 Plus' screen is much larger, at 5.5 compared to the iPhone 6's 4.7. We still consider the display size of the iPhone 6 to be big enough in order to make the user experience with the phone a joy, but of course, for those who just can't get enough screen on their mobile device, the 6 Plus can offer even more. And of course, the 5.5 panel will make stuff like various multimedia content even more enjoyable on the 6 Plus.
With regards to resolution, the 6 Plus also has the finer display. Its resolution of 1080 x 1920 pixels makes for the superb pixel density of 401 ppi. Of course, the iPhone 6 and its 750 x 1334 pixels (326 ppi) still display things in a crisp and beautiful way, but yeah, the visuals of the 6 Plus will be a notch cleaner.
Both panels feature great brightness output, with the iPhone 6 having the upper hand with its 600 nits, versus the 6 Plus' 570 nits. Meanwhile, though, the 6 Plus can get a bit dimmer (4 nits vs 7 nits), allowing for a slightly more comfortable viewing in the dark.
When it comes to color balance, the iPhone 6 once again has an advantage its color temperature is about 7150 K, while the visuals of the 6 Plus are a bit colder with their 7300 K (the ideal temperature is considered to be 6500 K, with higher numbers making for colder-looking (bluish) colors). Delta E values are also higher on the 6 Plus, suggesting an overall more color-inaccurate screen. Thankfully, its numbers are still low enough for it to be considered both natural and good-looking, but it comes to show that it's not that easy to produce a super-sized touchscreen with great color characteristics.