It has been addressed a couple of times but now, it is time to put this question to bed. Indeed, there is a big difference between this type of unit as compared to traditional units. Whether you are talking about hot rock or steam saunas, they will typically operate in excess of 200 degrees. As you know now, infrared units typically do so at much cooler and safer temperatures of 100 degrees to 140 degrees.
This heat decrease is not the only difference as traditional units will heat the air and not the body directly. What this can cause is an atmosphere that is so unbearably hot that it becomes suffocating. In addition, infrared units will penetrate human tissue instead of just heating the surface of the skin. Thus, this makes them much more efficient and effective.