In the Looks panel, you can not reorder Looks by dragging them, the order is fixed. Dragging over the Looks will change the active Look as you drag.
Double click on a Look to Rename it.
Create a New Look
This button creates a new Look at the same hierarchy level as the active Look. This is added at the bottom of the tree.
Create a Child Look
This button creates a new Look as a child of the active Look. If the Look already has children, it will be added at the bottom of the list.
Deletes the active Look, and all child Looks too.
Duplicates the active Look, and all child Looks too. The duplicate Look will has the same name with the word 'copy' added.