fogginess vs opaqueness

fogginess and opaqueness both are nouns.

Word	Noun	Adjective	Verb	Adverb
fogginess	Yes	No	No	No
opaqueness	Yes	No	No	No

As nouns, opaqueness is a hypernym of fogginess; that is, opaqueness is a word with a broader meaning than fogginess:

fogginess: the quality of being indistinct and without sharp outlines
opaqueness: the quality of being opaque to a degree; the degree to which something reduces the passage of light

Other hypernyms of fogginess include opacity.

fogginess (noun)	opaqueness (noun)
the quality of being indistinct and without sharp outlines	the quality of being opaque to a degree; the degree to which something reduces the passage of light
an atmosphere in which visibility is reduced because of a cloud of some substance	incomprehensibility resulting from obscurity of meaning