The difference is that with search you get a whole range of linked resources, and up to now (it may change with AI-generated content going forward) the style of the content usually gives enough signal to make an assessment, as well as comparing content between sites, and you learn which sites to trust.

With ChatGPT, correct and incorrect information is presented identically. You have nothing to go on except falling back to web search to fact-check ChatGPT’s output. This can still be useful as a starting point, but a world with only ChatGPT and no web search would be horrible, would overall be a step back compared to a world with only web search and no ChatGPT.