Well, I'm not exactly sure about Worldcon. I've always gone to World Fantasy in the past. It's mostly like LTUE--except, instead of three or four bozos up there (one of which was me this year) you have people like Donaldson and Terry Brooks. They have almost exclusively panels with big discussions, along with some smaller things like readings. It's very professionally-oriented, with panels like 'The state of fantasy in the current market' and 'The must-read books of the year' along with panels on worldbuilding and things.
The real reason everyone goes, however, is to network. It's a professional convention, which means you go to try and make deals with people who you might not see in person for the rest of the year. As such, there are a lot of parties and informal gatherings where people stand around and chat.
From what I've heard, Worldcon is like this--only with an extreme fandom edge added to it. It's supposed to be insane. A professional con and a fandom con mashed together. Everyone in the biz says that the first, must-attend con is Worldcon. World Fantasy is a close second. So, I expect that everything you can do at WF will happen at WorldCon, and probably more, since more editors go. (For instance, Tor will send six people instead of three.)