1 - There are some key differences in the specifications of molecular weight in all of the collagen (i.e Nutracoll is a lower average molecular weight than Peptipro).
2 - also there are some key differences which allows them to be utilised differently. During the manufacturing process, different enzymes are used to hydrolyse the proteins, these enzymes cleave the proteins at specific amino acid sequences. So there are different chains in the Nutracoll & Peptipro products.
Essentially, the enzymes for Nutracoll Beauty Collagen, separates different amino acids than that of the NutraColl Joint product and Peptipro. Whilst they all use a similar base ingredient, the products have been optimised for specific performance.