Question: what is the difference between ipad 2 and ipad 4?
Answer: The iPad 4th Gen models have a 9.7-inch 2048x1536 (264 ppi) "Retina" Display that is much higher resolution and better quality than the "non-Retina" displays in the other two devices. By contrast, the iPad 2 has a 9.7-inch 1024x768 (132 ppi) display and the original iPad mini has a 7.9-inch 1024x768 (163 ppi) display.