I'm in the camp of believing Apple's product line-up is too big. It's having a huge negative impact on their software quality too.
Sport: cheaper model, a little better for athletic activity (screen is more impact-resistant but less scratch resistant)
regular: main model, styled more like a classic watch, screen is more scratch resistant but less impact resistant
Edition: made of gold, super-expensive
The Edition watch specifically isn't going to be confused with the other two models, and the Sport/regular split seems pretty straightforward to me.
I'm in the camp of believing Apple's product line-up is too big. It's having a huge negative impact on their software quality too.