radiance vs lambency

radiance and lambency both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiance	Yes	No	No	No
lambency	Yes	No	No	No

As nouns, lambency is a hyponym of radiance; that is, lambency is a word with a more specific, narrower meaning than radiance:

Other hyponyms of radiance include gleam, gleaming, glow, luster, lustre, sheen, shininess, burnish, gloss, glossiness, polish.

radiance (noun)	lambency (noun)
the quality of being bright and sending out rays of light	an appearance of reflected light
the amount of electromagnetic radiation leaving or arriving at a point on a surface
an attractive combination of good health and happiness