The level of MSM and Glucosamine is the same in both formulas. Both contain equal proportions of Perna canaliculus, Dimethylglycine, Manganese, Grape Seed Extract, Vitamin E, Vitamin C, Selenium, and Glutathione. The only noticeable difference is that a small quantity of Chondroitin Sulfate is added to the GlycoFlex Plus formula so that the biochemistry of some pets can use it well.