illuminance vs illumination

illuminance and illumination both are nouns.

Word	Noun	Adjective	Verb	Adverb
illuminance	Yes	No	No	No
illumination	Yes	No	No	No

As nouns, illuminance and illumination are synonyms defined as:

illuminance (noun)	illumination (noun)
the luminous flux incident on a unit area	painting or drawing included in a book (especially in illuminated medieval manuscripts)
	the luminous flux incident on a unit area
	an interpretation that removes obstacles to understanding
	the degree of visibility of your environment
	a condition of spiritual awareness; divine illumination