Well, we might have no practical test to discern between the two types, but, assuming we agree the two types are distinct in principle, then we might arrive at a classification using some inference based on their fundamental nature.

For example, we can safely say this AI algorithm:

  while true; do: echo "HELP, I'M A SENTIENT BASH SCRIPT"; done

... is probably not sentient. This is a conclusion that would not be immediately obvious, say, to a 15th century person, especially if you would pipe the output to a speech synthesizer, making the whole apparatus seem magical and definitely inhabited by some kind of sentient spirit.

My claim would be then that GPT-4 is more akin to the program above, in that it's a massive repository of world knowledge parsed by a recursive and self-configuring search algorithm, not very different in principle from a Google search and certainly not believably capable of an setting its own goals be in any sense distraught, in pain, or worthy of a continued existence. Now, I agree you can poke sticks at my inference, and that it will become harder and harder to make such claims, so prudence is advisable.