Thanks to your comment I came across this article, which I think explains agents quite well. Some differences seem artificial, but it gets the point across.
Were you thinking along these lines?
https://medium.com/@tahirbalarabe2/five-types-of-ai-agents-e...
"Agent" in the context of LLMs has always been pretty closely intertwined with advertising how dangerous they are (exciting!), as opposed to connecting to earlier research on reflexes. The first viral LLM agent, AutoGPT, had the breathless " (skull and crossbones emoji) Continuous Mode Run the AI without user authorisation, 100% automated. Continuous mode is not recommended. It is potentially dangerous and may cause your AI to run forever or carry out actions you would not usually authorise. Use at your own risk. (Warning emoji)" in its readme within a week of going live, and was forked into ChaosGPT a week later with the explicit goal of going rogue and killing everyone
Ref: Artificial Intelligence - A Modern Approach.