Pixel density is a measurement of a screen's resolution, expressed as the number of pixels per inch (PPI) on the screen. A higher pixel density translates into more clarity and sharpness for the images rendered on the screen, thus improving the quality of the viewing experience.
Resolution is an essential indicator of a screen's image quality, representing the maximum amount of pixels that can be shown on the screen. The resolution is given as a compound value, comprised of horizontal and vertical pixels.
The bigger the screen size is, the better the user experience.
4.has an LED-backlit display
Uses LED backlighting, resulting in better image quality, more vibrant colors and richer blacks.
5.has an ambient light sensor
An ambient light sensor adjusts the luminance of the device according to the amount of natural light that surrounds it.
Response time is how long it takes for a display to change the state of pixels, in order to show new content. The less time it takes to respond, the less likely it is to blur fast-changing images.