Well, I would say that when people at the moment say agent they mean what you call autonomous agent. Browsing or code interpreter is just LLM + tool use. I think there is a really large difference in quality between a system that just interacts 1-2 times with some tool/API before giving an answer and one that runs in a loop with undefined length (until it decides to terminate). It's like the difference between programming without loops or recursion vs with them. Night and day.