Neither technology is entirely new. Transparent displays have been popping up at trade shows for years, and rival LG has its own 55-inch mirrored OLED prototype that it showed off in 2014. But as OLED-info points out, Samsung's hardware is a bit more advanced than past efforts.
The transparent display, for instance, is the largest of any see-through OLED--save for a prototype from Planar that was likely manufactured by Samsung--and it has a wider color gamut, higher transmittance, and wider viewing angles than transparent LCDs. As for the mirrored display, Samsung says it has a much higher reflectance level than mirror LCDs, and it doesn't require ambient backlighting.
It's also worth noting that neither display is being referred to as a prototype by Samsung. While there's no word on availability, it's possible that Samsung could offer very limited quantities of these displays to the digital signage and retail markets. The mirrored display, for instance, could let people try on virtual clothing and view additional information on the screen. Samsung specifically mentions using Intel's RealSense cameras to take measurements as shoppers model for the mirror.
Why this matters: Digital signage and clothing sales don't exactly seem like the stuff of sci-fi. But we can at least imagine what this technology might bring in the distant future. We've all seen that wild-eyed video that imagines a world of persistent displays, serving important info wherever we look in their direction; that only becomes possible if ordinary surfaces like windows and mirrors get their own display tech. With every impressive tech demo, we inch a little closer.