opaqueness vs murkiness

opaqueness and murkiness both are nouns.

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

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

opaqueness: the quality of being opaque to a degree; the degree to which something reduces the passage of light
murkiness: the quality of being cloudy

Other hyponyms of opaqueness include cloudiness, muddiness, blurriness, fogginess, fuzziness, indistinctness, softness.

opaqueness (noun)	murkiness (noun)
the quality of being opaque to a degree; the degree to which something reduces the passage of light	the quality of being cloudy
incomprehensibility resulting from obscurity of meaning	an atmosphere in which visibility is reduced because of a cloud of some substance