Default [Q] Difference in display of same S4

Guys I am a S4 user from more than 6 months..Today one of my friend brought his S4 which is in stock condition and 5 months old as well..His screen is way more brighter than mine..Yes I was shocked too..I m rooted and using crash Rom plus domination theme but that does not matter i think ..I tried several apps to compare like stock browser,lock screen and camera.His screen has much glow and more brighter than mine.Both the phones have adaptive display mode on.My phone screen looks like dull..I can't show u the difference in picture because of camera quality..
Left S4 is mine and right one is brighter one..May be in picture there is no difference..
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