Each year they bring out three different sized models. Big, medium and small. Or you can buy an old one.

Yes there are feature differences, if you are a techie or a gamer or into photography, but bigger always means better. It really isn't rocket science.

The iPad and Mac laptop lineups are a bit of a mess at the moment though. I think that's mainly because they're in various stages of technology transitions such as retina displays, wide colour gamut, touch bar and Apple Pencil support. They're pushing aggressively into new technologies and manufacturing processes and I think that's creating problems for them.