slightness vs slenderness

slightness and slenderness both are nouns.

Word	Noun	Adjective	Verb	Adverb
slightness	Yes	No	No	No
slenderness	Yes	No	No	No

As nouns, slightness and slenderness are synonyms defined as:

Other synonyms of slightness include slimness.

slightness (noun)	slenderness (noun)
slenderness	the quality of being slight or inadequate
the property of an attractively thin person	the property of an attractively thin person
the quality of being unimportant and petty or frivolous	relatively small dimension through an object as opposed to its length or width