ChatGPT has a naive optimism. It reaches for airy, meaningless, slightly metaphorical statements right away (when asked to support something, not when explaining). It also uses simple, but very clean grammar, and has a bit of a thesaurus feel where it has no attachment to any particular word.

I've seen lots of people get it wrong, claiming that something is ChatGPT when it isn't. To my understanding, this is because they are negative matching - "this sounds weird, so it must be AI", or "this is wrong, so it must be AI", and not positive matching on ChatGPTs exact tone.