Refurbished means it was sent back to the factory for repair because someone complained the product was defective.
Whether the product was actually defective or not is debatable. And whether the factory deemed the product was defective or not is debatable. But it was assumed the product was defective to begin with. Thus, it got sent to the factory.
If the unit is purely a demo or a store return w/o any complaint that it was defective, it is called an "open box" item.
So, if the item is physically sent to the factory, it is refurbished. Otherwise, it is open box.