niceness vs sweetness

niceness and sweetness both are nouns.

Word	Noun	Adjective	Verb	Adverb
niceness	Yes	No	No	No
sweetness	Yes	No	No	No

As nouns, sweetness is a hypernym of niceness; that is, sweetness is a word with a broader meaning than niceness:

Other hypernyms of niceness include pleasantness.

niceness (noun)	sweetness (noun)
the quality of nice	the property of tasting as if it contains sugar
the quality of being difficult to detect or analyze	a pleasingly sweet olfactory property
a courteous manner that respects accepted social usage	the quality of giving pleasure
	the taste experience when sugar dissolves in the mouth