I knew it all along - however, it is nice when others figure it out too! A customer I had not seen in a while came in to buy a particular product the other day. I mentioned I had been missing them. They admitted they had been trading at BRAND X where a similar product was cheaper. However it did not seem to be working as well as our product. I asked if they had the one from BRAND X, they said no they hadn't even finished it, just threw the rest away. I explained why it may not have worked as well and told them why my product probably worked better.
Not all products regardless what it is (vitamins - minerals - pain medication) will work the same due to availability of the product through the base it is in. Some bases allow for better absorption than others. That is why there are so many different prices and products available.