sweetening vs sirup

sweetening and sirup both are nouns.

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

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

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

sweetening (noun)	sirup (noun)
the act of adding a sweetener to food	a thick sweet sticky liquid
an improvement that makes something more agreeable
something added to foods to make them taste sweeter