There are many differences! To start a fixed oil is a lipid (fat), which is a completely different type of macromolecule (***see attached pics***) than a protein. One of the most visible physical differences between the two is that fixed oils are non-polar molecules (hydrophobic="water-fearing"), meaning they will dissolve in water. Proteins are polar molecules (hydrophilic = "water-liking"), so they will dissolve in water.
