radiancy vs glossiness

radiancy and glossiness both are nouns.

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

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

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

radiancy (noun)	glossiness (noun)
the quality of being bright and sending out rays of light	the property of being smooth and shiny