I think its because of the habits they wear constantly seeing them wearing their hair unwrapped and down creates a different image of them in our heads. I recognize the white-haired nun, and then the scowler with a mole, but not the white haired twin tails, the raven haired freckled one, or the grey haired one with the hair tied back to the left. Oh and the other gray haired one on the left of long white haired.