Stef,
Each dress is different. If you have a look around the collars, Minnie Jane has embrodery on the collar, and a pattern in the material on the sleeve (maybe a lighter embrodery). Lizzie, nothing, plain material. Annie, embroidery, different colour sleeve to Minnie Jane's. Lottie, bottom collar is different colour/material to the top one. Maybe they had a pattern that was liked by each of the girls, and mum decided to snap it up while she had it. We all know most girls/sisters would never ever like the same design in dresses, and the embroidery, colours were used instead to show their individuality.
Victoria