I don't know about different brands, but there are concerns. We need to make sure the charcoal is made from wood, not bones. And, there are two basic qualities that I know of. One is not labeled USP, the other is. USP is for internal use. So, it is probably the better choice, but I still think we need to make sure that the product is made from wood. I understand some is made form bones which can carry disease including Mad Cow Disease. I guess we ought to do some research on the subject. USP grade is more expensive.
Charcoal is used for many different purposes, so being made from bones may not be a problem for something such as air filters. But, using it internally does not sound good. Because their is so much corruption and so little recognition of the problem with animal products, we need to do our research on the source of the charcoal.