Is there really a difference? I feel like if you don’t know something, that kind of makes you stupid, right? If you don’t know historical facts or mathematics—at least the harder stuff, like algebra or calculus—or if you don’t know about advanced political topics, then you’re kind of a stupid person, not just ‘ignorant.’
Ignorance is not knowing things (e.g. facts).
Stupidity is not being about to think about things (e.g. lacking reason, being unable to make a good decision even when given all the useful information).
Making a bad decision out of ignorance isn’t necessarily stupid. Making a bad decision despite knowing the consequences is.