radiance vs shininess

radiance and shininess both are nouns.

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

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

radiance: the quality of being bright and sending out rays of light
shininess: the visual property of something that shines with reflected light

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

radiance (noun)	shininess (noun)
the quality of being bright and sending out rays of light	the visual property of something that shines with reflected light
the amount of electromagnetic radiation leaving or arriving at a point on a surface
an attractive combination of good health and happiness