very very very different, because the AI image is intentionally attempting to realistically imitate an existing, living, human victim, and because hyper realistic child pornographic art is illegal.
Pedophiles have been making loads of AI child porn. But its legal as long as it doesnt attempt to "look realistic" whatever that means, and isnt trying to look like a real person. A hyper realistic painting of child porn would also be illegal.
Laws might change in the future, but currently AI child porn slips between the same lines that 2d cartoon child porn does.