PET protective film and PET release film are the same material - PET material, but for different uses, basically no big difference.
A little difference is: PET protective film is relatively thick, with anti-scratch effect; PET release film is relatively thin, there is no anti-scratch effect, used in the three-layer structure of the protective sticker, is to tear off. PET protective film is generally used as a use layer, PET release film is used as a protective layer to protect the PET protective film.