Purchasing agents do not know about ceramics so they like to compare numbers on data sheets when second sourcing materials. But this data sheet demonstrates an issue with that. Although they have dramatically different plasticities (as suggested by drying strength and drying shrinkage) the chemistry of these two ball clays gives no indication of this (nor can it). The No. 1 has a finer size, which means it should be more plastic, right? But it isn't. Ball clays are used in ceramics principally for their plasticity and only actual physical handling of the plastic material enables comparing this important physical property.
In ceramics, glazes and bodies have a chemistry, a mineralogy and a physical presence. All of these need to be understood to adjust and fix issues.