radiancy vs refulgency

radiancy and refulgency both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiancy	Yes	No	No	No
refulgency	Yes	No	No	No

As nouns, radiancy and refulgency are synonyms defined as:

radiancy and refulgency: the quality of being bright and sending out rays of light

Other synonyms of radiancy include effulgence, radiance, refulgence, shine.

radiancy (noun)	refulgency (noun)
the quality of being bright and sending out rays of light	the quality of being bright and sending out rays of light