What is the difference between simple infrared radiation and the TDP lamp?

The TDP lamp incorporates a mineral plate that is heated to ionize the trace minerals. This plate, the key distinct component of these TDP lamps, is composed of a proprietary mineral formulation consisting of 33 elements intended for healthful stimulation of the human body processes (in 43 chemical binding forms).

The human body relies on vitamins and minerals to repair and rebuild itself. When your immune system is weakened or you are fatigued, stressed, or have taxed your body in some way, you need minerals to rebuild and repair your health. Eighty percent of Americans are Zinc deficient. Premature grey hair can sometimes be attributed to a lack of Molybdenum. 
Key minerals essential to health are contained in the special mineral plate in the TDP lamp. When the plate is heated to the specific high temperature, it emits electromagnetic waves sized 2-25 microns, allowing for maximum absorption by the human body. 

The principle behind using the mineral plate is that the excitation of the minerals into their ionic state is what stimulates many of the body's natural metabolic processes, such as Fe(Iron) to Fe++ which is used in the process of oxygenating the blood. And the body uses minerals mostly in their ionic form, not their metallic form.

According to studies conducted in China and Korea, the TDP lamp has been clinically show to promote micro-circulation, that's the movement of blood in all the tiny spaces of your body so it can deliver nutrients, remove waste products, and send repair cells to do their work.