aspartame vs sweetening

aspartame and sweetening both are nouns.

Word	Noun	Adjective	Verb	Adverb
aspartame	Yes	No	No	No
sweetening	Yes	No	No	No

As nouns, sweetening is a hypernym of aspartame; that is, sweetening is a word with a broader meaning than aspartame:

aspartame: an artificial sweetener made from aspartic acid; used as a calorie-free sweetener
sweetening: something added to foods to make them taste sweeter

Other hypernyms of aspartame include sweetener.

aspartame (noun)	sweetening (noun)
an artificial sweetener made from aspartic acid; used as a calorie-free sweetener	the act of adding a sweetener to food
	an improvement that makes something more agreeable
	something added to foods to make them taste sweeter