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