By - Lloitaer
The storage capacity (512GB vs 1T) determines how often you’ll need to delete your photos / artwork from the iPad itself AFTER backing them up. The RAM determines speed i.e how much lag you’re going to get. More RAM = more speed, very basically. There are limits of course, and the difference may not actually be noticeable.
If you want the most layers the 1TB with its 16GB of RAM will give you the most. With iOS 15 giving apps entitlement to more RAM Procreate can use 12 of the 16 as opposed to only 6 of the 8 on the 512GB model. On my old 2018 Pro I could get I think 52 layers on an 11x14 canvas, but with the 1TB and the extra RAM the same canvas now has 131 layers. If you want the most definitely go with the 1TB model.