It uses an upgraded version of the chatbot that's been all over the news recently, and can access current news etc., which the now-famous chatbot cannot. Bing + AI is in Very limited preview at bing[.]com, there's a waitlist to access the full version, and AI related features in the Insider Dev version of Edge.
The basic idea in favor of AI search is instead of getting a list of links to check out, you get an answer. Problem is, when you get that list of links, 1/2 or more may feature inaccurate opinions &/or info, so which site does the AI choose for your answer? Microsoft acknowledges that this is a problem. Google is a leader in AI, but has felt that adding AI to search would be a bad move, maybe because they make tons of money on the ads shown on the search results page? Then Chat GPT [which Microsoft is invested in] arrived, and set off all sorts of alarms at Google -- yesterday they announced their own AI search coming soon.
bleepingcomputer[.]com/news/microsoft/microsoft-launches-new-ai-chat-powered-bing-and-edge-browser/
blogs.microsoft[.]com/blog/2023/02/07/reinventing-search-with-a-new-ai-powered-microsoft-bing-and-edge-your-copilot-for-the-web/
theverge[.]com/2023/2/7/23589587/microsoft-chatgpt-bing-ai-event-preview
theverge[.]com/2023/2/7/23589711/a-few-basic-videos-showing-what-microsofts-bing-chatbot-can-do