It's quite different. However Elite AI does not act like humans, they are still just bots.
They might declare war on you (and attack) if your reputation gets very bad. There will be a section in the newspaper with reputation, updated daily.
The main difference is that they make a lot more buildings and units and are generally just tougher.
There might be more gold users in those games, since it requires gold to join, but I wouldn't be sure of it. I've won a few Elite AI matches without encountering players that spend gold.
Yes the AI will be Elite-AI for all countries who are not human, or those that leave.
Try it, it can be OK fun, but don't expect a lot of human players in those games, so it might be a bit boring.
