There are topics, like
- expert systems (and, more generally, symbolic AI),
- artificial general intelligence,
- evolutionary computation (swarm intelligence, evolutionary algorithms, etc.),
- traditional search algorithms (such as A*),
- philosophical and social aspects of AI (such as super-intelligence, tests and definitions of intelligence, etc.)
that, as far as I know and interpret the on-topic page here, are not on-topic here, but are on-topic on AI SE. Some of them have little to do with statistics or machine learning (though some may disagree, as there may be a way to study these from a statistical point of view). So, there is not a perfect overlap between Artificial Intelligence SE and Cross Validated SE. However, there's a big overlap between the two sites, especially because machine learning (a big part of the two) is on-topic on both sites. Nevertheless, AI SE and Stats SE are significantly different to be separate sites. In any case, we should probably collaborate more, in some way, when it comes to machine learning questions. For instance, we could "advertise" our ML questions to each other, or something like that, so that askers can get an answer more quickly or likely.
The site that I really think has an almost perfect overlap with Stats SE is Data Science SE, though some may disagree (because Data Science SE maybe covers certain topics that are not very welcomed here, such as certain implementation questions).