Google's definition is sufficient[0]. I'd also go so far as to say that LLMs aren't even AI, but that can be a bit pedantic. I align with Richard Sutton's reasoning, in that LLMs (and GPT models more generally) aren't "intelligent" in the same way that RL models are[1].
Small-language models also use GPT. And I agree it's not "LLM vs RL" and that they're orthogonal, however, RL has features that more clearly resemble intelligence.