richness vs verdancy

richness and verdancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
richness	Yes	No	No	No
verdancy	Yes	No	No	No

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

Other hyponyms of richness include overgrowth, greenness, verdure, wilderness.

richness (noun)	verdancy (noun)
a strong deep vividness of hue	the lush appearance of flourishing vegetation
the property of a sensation that is rich and pleasing
the property of producing abundantly and sustaining vigorous and luxuriant growth
the property of being extremely abundant
splendid or imposing in size or appearance
the quality of having high intrinsic value
abundant wealth