Qualitatively, both arch supports and orthotics contour the plantar foot, apply support to the arches, reduce pronation of the foot and decrease internal rotation of both tibial and femeral segments. All of more than 100 different patents reported changes in posture consistent with clinical use of their device.
Quantitatively, the wedge part of orthotic design related to foot function has never been defined and measured. Some companies can tell you they have added 10 degrees to your neutral position cast but they can not tell you how much was in the neutral plate contoured to the cast, or how much angular tilt is present in their finished product. Ultimately the angular correction in the finished device is what changes human biomechanics and posture. Even though many researchers in the field of human biomechanics have understood the importance of this wedge in orthotic design, none have quantified the wedged portion of their device, and orthotic treatment has remained more of an art than a science.
Without quantification no one could define or measure the difference between the many different devices on the market.