A proximity sensor detects whether a person or object is in front of it. Typically it will use an infra-red (IR) transmitter to reflect light off a object and a receiver to detect light reflected back. In this respect it is basically a touchless button. Proximity sensors could also be considered a limited form of a distance sensor.
We use an ultrasonic distance sensor as a proximity and occupancy sensor in our smart shower" class="xref">.
We use an ultrasonic distance sensor as a proximity sensor for our smart mirrors" class="xref">.
