aspartame vs sweetener

aspartame and sweetener both are nouns.

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

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

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

Other hypernyms of aspartame include sweetening.

aspartame (noun)	sweetener (noun)
an artificial sweetener made from aspartic acid; used as a calorie-free sweetener	anything that serves as an enticement
	something added to foods to make them taste sweeter