incandescence vs luminousness

incandescence and luminousness both are nouns.

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

As nouns, luminousness is a hypernym of incandescence; that is, luminousness is a word with a broader meaning than incandescence:

Other hypernyms of incandescence include brightness, brightness level, light, luminance, luminosity.

incandescence (noun)	luminousness (noun)
light from heat	the quality of being luminous; emitting or reflecting light
the phenomenon of light emission by a body as its temperature is raised