I've had an iphone with LCD model 5755136 and I just got an iphone for my girlfriend that has LCD model 7451392. I'm quite surprised what a big difference there is. My iphone has a brighter display with much crisper whites and good grays, while hers is slightly dimmer with whites that are warmer/yellowish and browner grays. Maybe mine shows an overly cool color, but to me it's much more pleasing and crisp. When I only look at hers, it looks fine, but when they're together, mine seems much better. Do we know who manufactures the different models? the 5-series is to the right, 7-series to the left on the photo.