I, personally, tell the difference by paying attention to and observing reality without making any judgments. Then, I compare that with my expectations based on my judgments. If there is a difference, then I am thinking I am interacting instead of interacting.

Over time, I stop making judgments. And in essence, I stop thinking about interacting with the world, and just interact, and see what happens.

The less judgments I make, the more difficult the Turing Test becomes; as it is no longer about meeting my expectations, but instead satisfying my desired level of complexity. This, by the nature of real-world interaction, is a complicated set of interacting chaotic equations; And each time I remove a judgment from my repertoire, the equation gains a level of complexity, gains another strange attractor to interact with.

At a certain point of complexity, the equation becomes impossible except by a "god".

Now, if an AI passes THAT Turing Test, I will consider it a real person.