The one on the left is an SN13 in a beautiful purple color. The one on the right is an SN13 (different variety of 13) that changes color with the day. Sometimes it looks like a steel-blue-gray. At other times it is a steel-blue-purple. These make a really pretty duo. If anyone else has purple SN13's I would like to hear from you as I have some questions to ask about them as I would like to see the differences/similarities.