I think the big difference is just being an Autocompleter is less concerned with generating something that is truthful, as in reflects the real world as we understand it described by physics, vs simply spitting out something that sounds good.
Although we do have a litmus test in asking it "What is the meaning of life the universe and everything?"
Yes, exactly. An autocompleter is saying what the next words probably would be, not what it should be. It's like a chess program that tries to find the most likely move that a huan would make in the position rather than the best move.
That’s why I said “supervised” - in other words, someone competent in the domain and context is examining the output and correcting or discarding as necessary before use.
Although we do have a litmus test in asking it "What is the meaning of life the universe and everything?"