What is the difference between light and dark output modes?

Please note that light and dark modes have nothing to do with night, day or color sensing. It represents if the output is Normally open or Normally closed.
See below:

Light Switching: Thru beam and retroreflective systems (Output is ON with no object present); Proximity diffuse system (Output is ON with object present)

Dark Switching: Thru beam and retroreflective systems (Output is ON with object present); Proximity diffuse system (Output is ON with no object present)

Released for: Schneider Electric USA