Three types of Macbooks because of the size requirements but why three different types of watch?

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.

The watch types are really clearly differentiated though:

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.

There's really only one type of Apple Watch with hundreds of different external configurations. The hardware is identical in all of them.

Not sure if you're considering this or not but there are two sizes of watch so at least screen size is different. Which is pretty much inline with the differences between MacBook Pros and iPhones where screen size is the main delimiter.