What are you talking about...
4S - 640 x 960 pixels, 3.5 inches (~330 ppi pixel density)
S3 - 720 x 1280 pixels, 4.8 inches (~306 ppi pixel density)
So basically what you are saying Robbo (to clear up any doubt) is that IF the iPhone used the same display as the S3, it would be called a Retina Display given that "Retina Dsiplay" is an Apple brand which can only be used by them and it goes over their 300ppi for a mobile device?
Just to clarify....