slightness vs smallness

slightness and smallness both are nouns.

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

As nouns, smallness is a hypernym of slightness; that is, smallness is a word with a broader meaning than slightness:

Other hypernyms of slightness include littleness.

slightness (noun)	smallness (noun)
slenderness	the property of having a relatively small size
the property of an attractively thin person	lack of generosity in trifling matters
the quality of being unimportant and petty or frivolous	the property of being a relatively small amount
	the property of having relatively little strength or vigor
	The quality of being minor in influence, power, or rank.