aridity vs dryness

aridity and dryness both are nouns.

Word	Noun	Adjective	Verb	Adverb
aridity	Yes	No	No	No
dryness	Yes	No	No	No

As nouns, dryness is a hypernym of aridity; that is, dryness is a word with a broader meaning than aridity:

aridity: a deficiency of moisture (especially when resulting from a permanent absence of rainfall)
dryness: the condition of not containing or being covered by a liquid (especially water)

Other hypernyms of aridity include waterlessness, xerotes.

aridity (noun)	dryness (noun)
the quality of yielding nothing of value	objectivity and detachment
a deficiency of moisture (especially when resulting from a permanent absence of rainfall)	moderation in or abstinence from alcohol or other drugs
	the condition of not containing or being covered by a liquid (especially water)