1. Thirty percent faster CPU. 2. 16 gig memory is possible. 3. 1 terabyte SSD is possible. 4. New & better pen with color choices. 5. A very slight increase in screen real estate. 6. Slightly thinner. 7 New and maybe better GPU. 8. Anyone have any others? If I'm doing fine with the speed, memory size, & disk space of my SP3 Pro, I don't feel a strong need or deisre to order a SP4 Pro. If I did decide to purchase one, I would purchase the i7 16 gig 512 gig model.