Also the RCC it's the only one that uses the Septuaginta.
Jews and Protestants use the canon from the Masoretic Text.
Actually, I think the only ones who use the Septuagint are the Greek Orthodox. For most of its history, the Catholics have used the Latin Vulgate, as its “Old Testament” which was produced and translated into Latin using 5 or 6 versions available at the time, including the Septuagint. (Most of the other versions are partially or completely lost.)