Originally Posted by alanwarwic:
“A lower quality screen too I thought?
Though I would assume the slimness is more down to lower power requirements.”
Lower power requirements therefore slimmer battery, which is the majority of the bulk on an iPhone/iTouch.
The iTouch screen is lower quality, but the main difference in not having the IPS panel is a reduced viewing angle (which most of the time is irrelevant with that sort of device) and a reduced contrast ratio but still more than sufficient to provide a fairly black "black" provided you don't go mad with the brightness.
The iTouch 4 has half the RAM of the iPhone 4 so is less capable of multi-tasking, but is available in a model with twice the storage capacity.