Paywall
A paywall is a method of restricting access to content via a paid subscription. Beginning in the mid-2010s, newspapers started implementing paywalls on their websites as a way to increase revenue after years of decline in paid print readership and advertising revenue. In academics, research papers are often subject to a paywall and are available via academic libraries that subscribe.
Powerwall
A powerwall is a large, ultra-high-resolution display that is constructed of a matrix of other displays, which may be either monitors or projectors. It is important to differentiate between Powerwalls and displays that are just large, for example, the single projector display used in many lecture theatres. These displays rarely have a resolution higher than 1920x1080 pixels, and so present the same amount of information as on a standard desktop display. With Powerwall displays, users can view the display from a distance and see an overview of the data (context), but can also move to within arm’s length and see data in great detail (focus). This technique of moving around the display is known as physical navigation, and can help users to better understand their data.