From AD Systems article (link below)
What is the difference between high-energy and low-energy operators in automatic sliding doors?
Opening force, speed and actualization are the main differences between high- and low-energy operators. Automatic sliding doors with high-energy (also called full-energy) operators tend to open and close quickly. Because they operate with more force, these types of automatic doors are required to have safety devices installed along with the door assembly. High-energy automatic sliding doors can often be actualized by simply stepping into a sensor’s field of vision.
Low-energy automatic doors operate on demand through a knowing act—such as a push of a button, slide of a key card or a wave of the hand. They can also be operated through unknowing acts but will require safety devices if this is the case. This type of automatic sliding door opens and closes at a slower speed and with less force to accommodate the movement of individual or small groups of people.