These are other garments that are often confused but ultimately are not the same. The sacroiliac belt is responsible for providing stability and support to the pelvic area and the sacroiliac joint, so its dimensions are smaller and rarely become very wide.
The postpartum support is much larger as it covers the entire abdominal area from the base of the chest to the pelvic area, which gives it a much wider range of action. In addition in functionality it is also different since it helps to facilitate the process of reorganization of the internal organs after giving birth.