No, they're the same thing in America. We invented them here, after all.

But baking nachos takes time, so this guy's invention was spraying a cheese-like substance on top of some tortilla chips and selling them in stadiums and movie theaters. They're ubiquitous in those sorts of areas, so that's what we'd expect to get if we ordered some there, but if I ordered nachos in a restaurant and they brought me stadium nachos, I'd be upset.

It's the same difference between ordering a cheeseburger in a fancy restaurant and ordering one at McDonalds. They're essentially different products with the same name.