malnourishment vs undernourishment

malnourishment and undernourishment both are nouns.

Word	Noun	Adjective	Verb	Adverb
malnourishment	Yes	No	No	No
undernourishment	Yes	No	No	No

As nouns, malnourishment and undernourishment are synonyms defined as:

malnourishment and undernourishment: not having enough food to develop or function normally

malnourishment (noun)	undernourishment (noun)
not having enough food to develop or function normally	not having enough food to develop or function normally