How have they used it any differently? They didn't make a phone casing with it? Oh wait, that's right... they made enclosed devices without expandable storage.
You honestly don't know the difference? The One X and Lumia 800 are both a unibody with a totally different feel (important) to what Samsung have used.
People have praised the design and feel of those devices, not just the fact that it's polycarbonate therefore it's good. It's just a word used to refer to the slightly different design in most cases.