Biggest screen : SmartNamo Saffron 2- Dedicated to Mr. Narendra Modi

The smartphone with the biggest touchscreen in the world is SmartNamo Saffron Two, a phone dedicated to Gujarat chief minister Narendra Modi. The device has a 6.5-inch screen with 1920x1080p resolution and 338ppi pixel density.  

Screen: 6.5 inches
Screen Resolution: 1920x1080p
Pixel Density: 338ppi

Vivo Xplay 3S: 2K screen resolution

Chinese manufacturer Vivo has launched the world's first smartphone with 2K (2560x1440p) resolution, named Xplay 3S. This phone's screen has more pixels than the current crop of 1080p displays, making text, videos, images etc clearer and sharper. The new Vivo Xplay 3S's 6-inch display has pixel density of 490ppi, which is higher than the 469ppi (the highest pixel density before this launch) of HTC One.