There are lots of ways you can wear this top, it's just meant to be experimented with; you can have one side slung over one shoulder, you can wear it loose, tuck it up to create a top, or you can wrap it all around you and get all snuggly.
The size difference is in the arms and the width of the top. The arms are meant to be worn ruched at the wrist.
UK size 8-10
UK size 12-16
An unusual wrap top with a really large draped hood lined with matching lace and long sleeves.