Their LLM brand is now Gemini. Gemini comes in three different sizes, Nano/Pro/Ultra.
They recently released 1.0 versions of each, most recently (a few months after Nano and Pro) Ultra.
Today they are introducing version 1.5, starting with the Pro size. They say 1.5 Pro offers comparable performance to 1.0 Ultra, along with new abilities (token window size).
(I agree Small/Medium/Large would be better.)