Actually, in Chinese Medicine, those slight differences could mean the differences in whether they work for a person or not. They must be used at the right time for the right conditions. My doc and I almost started to use the Classical Pearls, but then I started making progress so I wanted to stick to what was working for me.
According to
www.classicalpearls.org/product-cat/formulas/ one of the main differences is that the Thunder Pearls are more for digestive issues (among other things), where the Lightning Pearls are more for cognitive issues(among other things).