I just got GDR3 for my L920 and I immediately noticed that the start screen was different. I don't know if it's more space between tiles or smaller tiles or larger right, left, and/or top margins for the tile area in relation to the screen itself. Unfortunately, I'm the kinda guy that notices doors are crooked in door frames and pictures aren't perfectly level so very subtle changes tend to catch my eye. I can't put my finger on the change--more space between tiles/slightly smaller tiles was the first thing to come to mind--but it is not something clearly documented and I don't currently have a screenshot to go back to and measure. My guess is that they adjusted the tile or margin sizes so they would fit better on 1080 screens and those subtle adjustments were implemented across the whole OS system so that 720 screens now have slightly different features that are intended to be almost unnoticeable except to those people who would pull out screen shots and zoom in to count pixels.