I would say that the iPad is not a tablet because it doesn't have a x86 processor nor does it run Windows Tablet Edition. The iPad is a larger smartphone, and the iPad Mini is a smaller larger cell phone.
I hope I don't sound ridiculous because someone miscategorized the iPad in the same category as Windows XP Tablet Edition.
Have you used both? Two very different experiences.
So I'm saying the two categories are insufficient. The iPad mini is a compact iPad. It's a third category. 7" tablets are more like large smartphones.