The 500mg and one,000mg refers to the Bodily volume with the cartridge. A full gram and half gram. There isn't a change in potency, just dimensions. A: To put it simply, a CBD cartridge is actually a small cylindrical tank, prefilled with CBD extracts in the shape of e-juice http://cbdhempexperts.blogsmine.com/5315227/cbd-cartridges-can-be-fun-for-anyone