There is no difference in quality as these are all 100% full top grain leathers which is the highest quality available for leather furniture. Leather Grades are actually just pricing groups. While some retailers will lead you to believe that they are indicators of quality in the hopes a consumer will spend more on a higher "grade", the reality is that all of these leathers are the same quality but the price is different for each due to the processes and chemicals needed to achieve that finish. When the hides arrive to the tannery, they are ALL the same quality and then depending on what is done with them to get a certain color or finish will impact the final price. (Grade)
In fact, depending on supply, demand and popularity, each of these leathers can move up or down in grades based on the current price from the tannery. While the quality never changed, the price did and so it is assigned a new pricing grade.