leanness vs sparseness

leanness and sparseness both are nouns.

Word	Noun	Adjective	Verb	Adverb
leanness	Yes	No	No	No
sparseness	Yes	No	No	No

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

Other hyponyms of leanness include wateriness, abstemiousness, spareness, sparsity, thinness, thinness.

leanness (noun)	sparseness (noun)
the property of having little body fat	the property of being scanty or scattered; lacking denseness
the quality of being meager