[Windows Central Question]

what is the diffrence between normal lumia 920 & AT & T lumia 920??
as I am using normal lumia 920 & my friend has At & t version
I found that his display is very good & rich as compare to me & even camera & video quality is good in his phone why so??

[jmshub]

There is no "regular" version of the 920. According to wikipedia ( Nokia Lumia 920 - Wikipedia, the free encyclopedia ), there are four variants of the 920. at&t didn't do any trickery in the 920 like they did later with the 1520, the only difference is that the RM-820 variant is designed to use at&t's wireless frequencies.

Did you buy your 920 new? If not, it is possible that the phone had previously had it's screen broken and replaced by a lower quality replacement.

[RumoredNow]

what is the diffrence between normal lumia 920 & AT & T lumia 920??
as I am using normal lumia 920 & my friend has At & t version
I found that his display is very good & rich as compare to me & even camera & video quality is good in his phone why so??

There are screen settings that can be tweaked and that may be the difference.

Settings > display > color profile - and - brightness profile is a good place to start > turning on "Sunlight readability" may also give you some benefit.

Check any settings that can affect the screen and you'll soon have it dialed in as you like. The 332 pixels per inch IPS LCD screen is very capable.

[xandros9]

There is no major difference between variants of the same phone typically from a hardware perspective - the 920 is identical all over the world save for differences in color, band support and perhaps some branding.
(like AT&T models have an AT&T globe logo)