lemon grass vs flavouring

lemon grass and flavouring both are nouns.

Word	Noun	Adjective	Verb	Adverb
lemon grass	Yes	No	No	No
flavouring	Yes	No	No	No

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

lemon grass: fragrant leaves of Cymbopogon citratus, used in cooking, in traditional medicine and are often found in herbal supplements and teas.
flavouring: something added to food primarily for the savor it imparts

Other hypernyms of lemon grass include flavorer, flavoring, flavourer, seasoner, seasoning.

lemon grass (noun)	flavouring (noun)
fragrant leaves of Cymbopogon citratus, used in cooking, in traditional medicine and are often found in herbal supplements and teas.	something added to food primarily for the savor it imparts
a tropical grass native to India and Sri Lanka
an aromatic oil that smells like lemon and is widely used in Asian cooking and in perfumes and medicines