sweetening vs aspartame

sweetening and aspartame both are nouns.

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

As nouns, aspartame is a hyponym of sweetening; that is, aspartame is a word with a more specific, narrower meaning than sweetening:

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

Other hyponyms of sweetening include honey, saccharin, refined sugar, sugar, sirup, syrup, cyclamate.

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