It's just a broad term for whatever AI integration they put into their various Apps and services. So, a combination of the neural engine stuff they've been doing for years, and integration with white label AI services from Google or OpenAI.

Siri is basically unchanged, it looks like they have had serious problems getting LLMs, or generative AI in general to be reliable and 'safe' enough to put their own name on it. By 'safe' I mean thinks like not generating emails based on Mein Kampf, or doodles of genitals, or hallucinating false 'facts'.

Not a concern for many of the frontier AI providers with no reputation to burn, but not exactly on-brand for Apple. I very much doubt Jobs would have viewed that differently.