Funny to think that the original Mac was 512 × 342 — one app icon is bigger than that today. 1  The iPhone fits between the app icons. 2  Four iOS devices fit comfortably on the iPad Pro resolution. If you are interested in a comparison of physical dimensions, then the difference is still striking. Here’s the original iPhone (3.5 inch screen) versus the iPad Pro (12.9 inch screen) … you can probably fit about nine in total.