sickness vs malady

sickness and malady both are nouns.

Word	Noun	Adjective	Verb	Adverb
sickness	Yes	No	No	No
malady	Yes	No	No	No

As nouns, sickness and malady are synonyms defined as:

sickness and malady: impairment of normal physiological function affecting part or all of an organism

Other synonyms of sickness include illness, unwellness.

sickness (noun)	malady (noun)
impairment of normal physiological function affecting part or all of an organism	impairment of normal physiological function affecting part or all of an organism
the state that precedes vomiting	any unwholesome or desperate condition
defectiveness or unsoundness