lead poisoning vs illness

lead poisoning and illness both are nouns.

Word	Noun	Adjective	Verb	Adverb
lead poisoning	Yes	No	No	No
illness	Yes	No	No	No

As nouns, illness is a hypernym of lead poisoning; that is, illness is a word with a broader meaning than lead poisoning:

lead poisoning: toxic condition produced by the absorption of excessive lead into the system
illness: impairment of normal physiological function affecting part or all of an organism

Other hypernyms of lead poisoning include malady, sickness, unwellness.

lead poisoning (noun)	illness (noun)
toxic condition produced by the absorption of excessive lead into the system	impairment of normal physiological function affecting part or all of an organism