sweetening vs flavouring

sweetening and flavouring both are nouns.

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

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

Other hypernyms of sweetening include flavorer, flavoring, flavourer, seasoner, seasoning.

sweetening (noun)	flavouring (noun)
the act of adding a sweetener to food	something added to food primarily for the savor it imparts
an improvement that makes something more agreeable
something added to foods to make them taste sweeter