the purpose is all pretty much the same they all just accomplish it to varying degrees. masks and butter are typically more thick and long lasting, but it really depends on the product. you can interchange them as long as you feel your lips are still healthy and moisturized
lip oils are usually made by more makeup brands than skincare/wellness ones, and most that iโve tried are more cosmetic than function for hydration. they are not necessary and often not useful except for their prettiness