I would bet that because one is a laydown and one is an upright that they needed to be able to distinguish which brush is which, so you have the 2 different names.
I believe both brushes are from Japan but I could be wrong. Which would explain why there are no serrations on them. If the brush was made at Keystone then there would be no reason why not to use the mold that puts the serrations in the brush. Just my $.02