illness vs prostration

illness and prostration both are nouns.

Word	Noun	Adjective	Verb	Adverb
illness	Yes	No	No	No
prostration	Yes	No	No	No

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

illness: impairment of normal physiological function affecting part or all of an organism
prostration: an abrupt failure of function or complete physical exhaustion

illness (noun)	prostration (noun)
impairment of normal physiological function affecting part or all of an organism	the act of assuming a prostrate position
	abject submission; the emotional equivalent of prostrating your body
	an abrupt failure of function or complete physical exhaustion