The iPad mini is where things get interesting. Its smaller size necessitates a few sacrifices, and the Retina Display (at this point) simply cannot be made to fit the new small chassis, so to speak. But lo! The difference between the 4th Gen and the mini is not that huge when examined under the microscope. In fact, the pixels of the Retina Display are only 2/3 the size of the iPad mini. In the older iterations, the pixels of the 4th Gen are ½ the size of the older versions, or .50. Here, they’re a full 16% (.16, since the 4th Gen’s pixels are 1/3 or .66 of the size of the mini) larger in comparison. This means the difference between the two, is less noticeable. In fact, to the naked eye, it’s negligible. Why is this? Since it’s a smaller screen, the pixels are packed much more densely.
Take a look at the images below or hit the link for further analysis.