Which is the difference between collagen fluid and collagen serum?

The only difference between the collagen fluid and collagen serum would be in the percentage of collagen used, other ingredients that might be included in a serum and the origin of the collagen itself. The most effective collagen comes from mammal sources, as it is the closest molecular structure to our own skin collagen. Phyto (plant) collagen and marine collagen would be from sources not related to human skin structure. Pure & Simple Skincare's pure Swiss Collagen Fluid is 96% pure collagen of a mammalian nature, and has only glycerin and sodium benzoate in trace amounts. Additionally, it has been micronized so the smaller molecular weight penetrates skin more effectively to help retain moisture naturally. For more information, go to www.pureandsimpleinc.com.