Drawing Tablet with screen has much more useful apps for an illustrator or graphic designer than an iPad. It's running Windows so you can use the full versions of Adobe CC and other professional Applications. Not just some dumbed down doodling apps.
You can use the pen display tablet companion either connected to your Mac or PC as a screen & drawing tablet or standalone running Windows. You can't connect the iPad to a Mac or PC, you are limited to what iOS can do. you only get a much more limited device.
I have the 11.6" XP-Pen Artist 12 Drawing Tablet Monitor . That is just the screen without a computer. Personally I wouldn't even trade that for an iPad.
