saccharin vs sweetening

saccharin and sweetening both are nouns.

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

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

saccharin: a crystalline substance 500 times sweeter than sugar; used as a calorie-free sweetener
sweetening: something added to foods to make them taste sweeter

Other hypernyms of saccharin include sweetener.

saccharin (noun)	sweetening (noun)
a crystalline substance 500 times sweeter than sugar; 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