clearness vs visibility

clearness and visibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
clearness	Yes	No	No	No
visibility	Yes	No	No	No

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

clearness (noun)	visibility (noun)
free from obscurity and easy to understand; the comprehensibility of clear expression	quality or fact or degree of being visible; perceptible by the eye or obvious to the eye
the quality of clear water	capability of providing a clear unobstructed view
	degree of exposure to public notice