Gemini is also the brand name for the end-user web and phone chatbot apps, think ChatGPT (app) vs. GPT-# (model).
Gemini Advanced is the paid subscription service tier that at the moment gets you access to the Ultra model, similar to how a ChatGPT Plus subscription gets you access to GPT-4.
Honestly, they should have called this part Gemini Chat and Gemini Chat Plus, but of course ego won't let them follow the competitor's naming scheme.