The retail dummy unit, otherwise known as the SAA-E3 as marked on the motherboard is a unit to showcase the PlayStation 4 design of the phat model. Internally it contains a motherboard, 2 controller inputs, and a micro-USB input at the back to power up the showcase LED-strip (hidden behind a ethernet port opening). Because it's a dummy it cannot boot up and play games because the internal hardware is not present. It can only be used as a display prop.
Kiosk / Demostations
Kiosks/Demostations are used in retail stores for tryout. They come in various models, depending on the store layout. Some also come with a PSVita on the side of it, while the PlayStation 4 is being displayed in the middle. They are not in production anymore and are quite hard to find. In rare cases you can find them on eBay.