The bright one is Small and the blue grey is the large size.

(description from magknits.com)

The hat was designed to use that odd ball of Noro Kureyon. You know the one, you had to have it but didn't want a whole sweater's worth. Or you had a whole sweater's worth and there is a ball left over. This is a great way to use up that ball of yarn and practice your fair isle. The self striping Noro Kureyon makes it look more like one of the more complicated fair isles that have several background colors.