What is the Difference Between a Motion Detector and a Presence Detector?
A motion detector has less detection areas so is less sensitive and generally designed to detect a movement of an arm. It is best suited to high traffic areas such as hallways.
A presence detector is significantly more sensitive so will detect finer movement such as a hand moving. They are designed for environments with low amounts of movement such as offices and sitting areas.
In both cases, as you get closer to the detector it will be more sensitive. The mounting height will also affect the sensitivity as well as the manufacturer specified detection area.