It's where you have to destroy your opponent's fortresses before they destroy yours. You know those forts that appear on some maps and can be upgraded with trebuchets? Fortresses are basically like those, only they have more health(about 15000 compared to the normal 10000).

There is no difference. It's the same thing. No idea why it has two names, but fortress seems to be the more common thing to call it. I guess "structured defense" is just a more technical term.

Yeah, that's what I am talking about. Not so much what we as players call it... but when you play a custom game, I am pretty darn sure that it is called Fortress mode in-game.

And I am pretty sure that's the same in the single player tournament.

I was just checking to make sure that it wasn't some fourth gametype that I didn't know about. As it is it's just a confusing inconsistency.

Thanks guys!