A calculator gives you exact results for a very small subset of problems (equations).
Chat-GPT will give you approximate (and occasionally incorrect) solutions to an extremely wide range of problems.
The main problem with AI is that there are only so many problems where an approximate solution is fine, and an incorrect solution is easy to work around. In order for AI to be broadly useful, it has to get to the point where it's correct more often than an expert human. It may well get there within the next couple of years, but this isn't a space LLMs are designed to be able to solve so it's not as guaranteed as a lot of people seem to think.