To move a specification or selection item, click "Edit" next to the item on the Specs/Selections page.
From there, you can change the item's category and/or name. Once you click "Update Item" at the bottom of the screen it will move the item to its new location.
To control the ordering of items within a category, you can use numbering in front of the item name. Otherwise, items within the same category will be ordered alphabetically.