LLM is a form of AI, specifically the text AIs like ChatGPT that have suddenly made "AI" a dinner table term. AI in some form or another is almost definitely being used in your device - even for things like filling in gaps in low-quality voice calls, and probably has been for a while. But the problem is that unlike those "old" AIs, LLMs require some significant power to run, so running them on phones will probably require meaningful trade-offs. But the increased security is also a meaningful benefit.