the hakari band of BW's have vitamins and extra stuff added into them. Others don't. Basic brands of BW's don't have all the nutrients that bettas need for their diet.
i think san fran bay does too. sfb and hikari are both excellent brands. a friend of mine has the tetra bloodowmrs and not only do they not have vitamins but they are all broken and deformed. she even found a twig in her can! the hikari ones are clean and even. the sfb ones kind of look like the tetra ones though...