leanness vs thinness

leanness and thinness both are nouns.

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

As nouns, leanness and thinness are synonyms defined as:

Other synonyms of leanness include spareness.

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

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

leanness (noun)	thinness (noun)
the property of having little body fat	the property of having little body fat
the quality of being meager	relatively small dimension through an object as opposed to its length or width
	a consistency of low viscosity
	the property of being very narrow or thin
	the property of being scanty or scattered; lacking denseness
	The property of lacking substance or strength.