We can see the difference: consider 600 dpi printers. 
LG's 5-inch 1080p smartphone display goes far beyond Retina pixel density
Apparently not content with the 1024 x 768 resolution on its 5-inch Optimus Vu, LG is working on a 5-inch 1080p smartphone display for the second half of 2012. The 1920 x 1080 touchscreen offers a wonderfully excessive pixel density of 440 ppi, which is 72 percent more pixels per inch than the Optimus Vu, and a third more than the display on the iPhone 4S. Unlike the display on LG’s current 5-inch phone, the new screen will have the same 16:9 widescreen aspect ratio as the HDTV in your living room. The display technology is the same IPS-based LCD that LG has offered in recent devices like the Nitro HD and aforementioned Optimus Vu, but with the added benefit of many, many more pixels. If you're eager to get an early look at the...