Collagen and Whey protein both contain different amino acids which assist in aiding the body and supporting protein levels. However, individually they contain different ingredients, different nutritional profiles are are for different goals.
Collagen is a structural and fibrous protein that is in all humans and mammals. It's an imperative building block in muscle, bones, tendons and ligaments and plays a huge role in the hair, skin and nail health. It is often known for it's anti-aging properties as the body's natural production of collagen begins to slow in your 20's. Collagen contains 8 essential amino acids and 19 amino acids, the main ones include: arginine, hydroxyproline, proline and glycine.
Whereas, whey protein is one of the two primary proteins and is found in milk. It contains 9 essential amino acids and 20 amino acids meaning it is a complete protein source. Notably, essential amino acids cannot be produced by the body and can only be obtained from the diet.
Ultimately, Whey Protein and Collagen aren't interchangeable as they contain differing amino acid profiles. Neither Collagen or Whey Protein are vegan products as they are derived from animals. Consulting with your doctor before starting a supplement routine is crucial to learning what is suitable for you and your health.