I always knew how to dissociate twins in general, because I study Arts & Anatomy since I'm 4, so I have a sharp eye. ;) But well, if you don't know how to dissociate James & Oliver, here are some clues :
Face: Oliver has a longer face than James. and his jaw is set differently then James’. James’s face is a little rounder, and Oliver’s a little skinnier.
Scars: James has a scar on his left eyebrow.
Moles: Oliver has a mole on the right side of his neck, and James on is left arm.
Eyes: Oliver’s eyes are a bit more slanted than James’. James’ eyes are not necessarily bigger, but wider. James has deeper eyes than Oliver. Oliver’s eyes slant down towards the outside corners a lot more than James’ do.
Nose: Oliver has a bump to his nose, whereas James doesn’t. Oliver’s is longer and curved, whereas James has a shorter out-curved nose.
Mouth/lips/smile: Oliver’s’ smile has a curve on the top left and right part of the upper lip. Oliver’s smile is kind of crooked. Oliver’s top lip is curved while James’ is straight.
Height: Oliver is the tallest of the twins!