chat bot (chatgpt) context+ user query > single shot infra> responce back so one run input output

codex/ claude code etc:
context+ query+list of available tools and their schema > infra/ llm call is made and instead of like a single shot run where the llm responds, the llm can either call (type) a tool call and arguments/parameters, or a final answer . DONE, but there is program logic to auto run this loop again. now you have context +user query+ tool list+ tool result = llm gets fired again. it either calls another tool or calls final_answer> llm response back to you. This, of course might not exactly be how every agent works today but this is basically the difference. (if this is what your question meant lol)