The difference is clear.

Mirrors always fog up after being exposed to steam from a steamy bath or shower, which means that you will need to wipe the mirror or wait for the fog to dissipate before you can use the mirror. You will not have to sit around and wait for the condensation to evaporate off of your mirror any longer with a demister by Demista. Mirror demisters are an excellent solution because they convert virtually any mirror into a heated mirror, thereby preventing condensation from forming on the glass surface of the mirror. Because they are available in such a wide variety of forms and dimensions, it is possible to use them with virtually any kind of mirror. They are easy to install, and because they are self-adhesive and stick to the back of the mirror, they are hidden from view. This makes them very convenient. Demister pads by Demista are manufactured in the United Kingdom to the highest standards possible and are subjected to a series of very stringent quality assurance tests by Demista. Demista mirror heat pads are full tested by Intertek and carry BEAB, UL and ULC approvals.