There is none. No one understands what intelligence really means or self-awareness. Which is why they feel threatened by anything that challenges their self proclaimed uniquely human trait. The goal posts WILL move a lot more before this debate is settled. Inevitably the success rate and accuracy of LLM responses is going to get better and better, quite possibly to the point where it is indistinguishable from a human. But it wont matter, because some humans will redefine intelligence to be something else so their place at the top of the intelligence pyramid remains in place.