The part that stands out to me is a higher percentage of the red & white combo. If these fall into the 'slag' category- wasn't it once said that red slags were less common, comparatively speaking? Compared to purple, amber, blue, green, etc?
So, the branch in the road could dictate that the red & white combo were made in a place that red glass was more available, or a time where red glass was more available.
Plus, the quality of the red & white combo's seem to be a bit higher. That's my opinion