Earlier quoted context omitted.
it uses PaLM 2 - which is an LLM trained from scratch. https://en.wikipedia.org/wiki/PaLM
And indeed, PalM 2 Bison is one of the LLMs covered in discussed link. That doesn't change the fact that chat apps like Google Bard and Microsoft Bing, and even the ChatGPT app with plugins, are not foundational LLMs. The fact that they incorporate information from outside the LLM (usually in ways that are opaque to the user) gives them fundamentally different characteristics to LLMS.
if you ask ChatGTP for today's weather (or for the state of the stock market), then it will probably turn to a plugin for the answer - still the plugin is answering some defined type of questions. I am not sure if that's a great deal.