The distinction is anything but blurry on the "classic" tablet size, which is 10 inches. Blown-up, simply upscaled phone apps look
horrible on 10-inch tablets, and this is where iOS has a
commanding lead over Android. After all, the Play Store until recently was
hiding which apps were "tablet-optimised" or not, because compared to iOS, there are so relatively few of them. It's rather comical when Android evangelists try to deny that.