iPhone 4 Superimposed over iPhone 5
Assuming the two phones are the same dimensions, the screen is definitely larger and the bezel smaller. It looks to be about 4 inches. It's hard to tell if the aspect ratios are the same, although this image suggests the 5's screen might be slightly taller, yet not a whole row of icons taller.
I used a skew tool to overlay the phone, not a perspective tool, so it might be a little off.

Assuming the two phones are the same dimensions, the screen is definitely larger and the bezel smaller. It looks to be about 4 inches. It's hard to tell if the aspect ratios are the same, although this image suggests the 5's screen might be slightly taller, yet not a whole row of icons taller.
I used a skew tool to overlay the phone, not a perspective tool, so it might be a little off.