Curiously, the 2DS is even more of a tablet-style system than it appears at first glance, as it actually features a single large screen in its center, not two separate ones. As one of their cost-cutting design measures, Nintendo reduced the number of screens in the system from two to one, and the appearance of separate screens is merely simulated by the way the case masks out the extraneous portions. This means the entire screen is by necessity a touchscreen, with the upper screen protected by a layer of plastic that sits above it.
It's one big touchscreen but they broke it up into two with plastic, then blocked the touch input on the upper one with a covering.