The VG cartos are at least primarily - if not totally - based on VG (Vegetable Glycerin). The other, premium cartos are primarily PG (Propylene Glycol) based and are in V4L's new, high end cartomizers. In general, VG-based liquids tend to provide more vapor and a lot of folks think that PG-based liquids tend to provide more flavor. Some people prefer one over the other, either because of a sensitivity to either PG or VG or because of a preference on the flavor or amount of vapor.