cloudiness vs cloud cover

cloudiness and cloud cover both are nouns.

Word	Noun	Adjective	Verb	Adverb
cloudiness	Yes	No	No	No
cloud cover	Yes	No	No	No

As nouns, cloudiness and cloud cover are synonyms defined as:

cloudiness and cloud cover: the state of the sky when it is covered by clouds

Other synonyms of cloudiness include overcast.

cloudiness (noun)	cloud cover (noun)
the quality of being cloudy	the state of the sky when it is covered by clouds
the state of the sky when it is covered by clouds
gloomy semidarkness caused by cloud cover