From some philosophical standpoints (determinism, for example), a person is their mind, a brain; so reproducing or simulating the brain to a very high degree would result in reproducing that person. Whether that is true or not is philosophical, and is similar to the Star Trek teleporter discussion.

In Alastair Reynolds’ Revelation Space universe, the classification is pretty sensible: there are three levels of simulation.

Alpha level is a nanotech scan-copy of a real brain which kills the subject, but the resulting persona is considered intelligent, a human, with rights and all. IIRC there were only 60 people who did that.

Beta level is a model built upon all available information about the person, all audio, video, text, etc. This is pretty much what we might now call a trained AI, but it is not considered intelligent.

And gamma level is a fully artificial persona, usually used for chatbots and what we would use LLMs for now.