simple vs half-wit

simple and half-wit both are nouns.

Word	Noun	Adjective	Verb	Adverb
simple	Yes	Yes	No	No
half-wit	Yes	No	No	No

As nouns, half-wit is a hyponym of simple; that is, half-wit is a word with a more specific, narrower meaning than simple:

simple (noun)	half-wit (noun)
a person lacking intelligence or common sense	a stupid incompetent person
any herbaceous plant having medicinal properties	a person of subnormal intelligence

simple (adjective)	half-wit (adjective)
(botany) of leaf shapes; of leaves having no divisions or subdivisions
having few parts; not complex or complicated or involved
easy and not involved or complicated
exhibiting childlike simplicity and credulity
unornamented
lacking mental capacity and subtlety
apart from anything else; without additions or modifications