No, not all protein sources are equal. Beyond the source itself (animal or plant-based), we also distinguish between complete and incomplete proteins.
A protein is considered complete when it contains all 10 essential amino acids that a dog requires. These are almost exclusively animal-based and are highly digestible and "bioavailable," meaning the dog's body can easily absorb and utilize them almost entirely.
An incomplete protein, on the other hand, is missing one or more of these 10 essential amino acids. These are typically found in plant-based proteins or low-quality animal by-products. They are harder to digest and require more effort from the kidneys and pancreas to be processed and eliminated.