Many people don't want to buy store brand items because they feel they might be inferior. When I worked at Ross Frozen Foods in England (a lifetime ago), we packaged foods with both the Ross label and labels for local supermarkets such as Waitrose, which company by the way, has a royal seal. The contents were no different, just the packaging changed. The reason for this is the store purchases large quantities and can therefore sell it at a lower price, but the producing company doesn't want it to compete with the price they are selling their name brand product for.
Bottom line is, there is no difference between name brand and store brand.