I'm pretty sure most people see a huge difference between a old-style MacBook Air screen and a MacBook Pro screen. The Air is a 1080p 13in display. The Pro isn't even 4k, but the difference is extremely noticeable, especially if you are looking at a document or code (even from 24-36 in away). Seeing the difference between Apple's retina display and 4k? Well, that is difficult.