luminousness vs luminance

luminousness and luminance both are nouns.

Word	Noun	Adjective	Verb	Adverb
luminousness	Yes	No	No	No
luminance	Yes	No	No	No

As nouns, luminousness and luminance are synonyms defined as:

luminousness and luminance: the quality of being luminous; emitting or reflecting light

Other synonyms of luminousness include brightness, brightness level, light, luminosity.

luminousness (noun)	luminance (noun)
the quality of being luminous; emitting or reflecting light	the quality of being luminous; emitting or reflecting light