Basically, what we used to call a "secretary" or these days called personal assistant.
I do not agree with the analogy because a secretary does not have the level of knowledge that the AI agent has. They will be more like advisors, experts in the field you need who will be there to help you with whatever you need and carry out the tasks you entrust to them.
what different about AI agents and ChatGPT?
That they can perform tasks autonomously. You have to give ChatGPT instructions each time.