pleasantness vs sweetness

pleasantness and sweetness both are nouns.

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

As nouns, pleasantness and sweetness are synonyms defined as:

pleasantness (noun)	sweetness (noun)
the quality of giving pleasure	the property of tasting as if it contains sugar
the feeling caused by agreeable stimuli; one pole of a continuum of states of feeling	a pleasingly sweet olfactory property
	the quality of giving pleasure
	the taste experience when sugar dissolves in the mouth