sweetness vs taste sensation

sweetness and taste sensation both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweetness	Yes	No	No	No
taste sensation	Yes	No	No	No

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

sweetness: the taste experience when sugar dissolves in the mouth
taste sensation: the sensation that results when taste buds in the tongue and throat convey information about the chemical composition of a soluble stimulus

Other hypernyms of sweetness include gustatory perception, gustatory sensation, taste, taste perception.

sweetness (noun)	taste sensation (noun)
the property of tasting as if it contains sugar	the sensation that results when taste buds in the tongue and throat convey information about the chemical composition of a soluble stimulus
a pleasingly sweet olfactory property
the quality of giving pleasure
the taste experience when sugar dissolves in the mouth