Poster site, most often a 4- or 6-sheet, which is 'back-illuminated'. Posters used in this type of site normally have to be printed on special material, eg vinyl.
A backlit sign, internally illuminated, generally with fluorescent lamps, which displays a photographic, digital, or printed graphic that is usually sandwiched between two acrylic faces. May be wall-mounted, inset into a wall, freestanding, or built into a store fixture. A line-voltage electrical fixture, which legally must be UL-listed to be used safely in a commercial or retail space.