Who creates the Photo Box album in iPhoto iOS 7.1?

It is one of the automatically created albums, see this help page:

What are albums? http://help.apple.com/iphoto/iphone/2.0/?handbuch#blnkb9b1e2a

Photo Box: If a photo appears in an album (Edited, Favorites, Journals, or custom) and you delete the photo from your device, the photo remains in the album. If you remove the photo’s edits and tags, or delete the photo from the journal, iPhoto moves the photo to the Photo Box album (and removes it from the album it was in). If you edit or tag a photo in the Photo Box album, or add it to a journal, the photo is removed from the Photo Box album (and added to the appropriate album).

Basically, iPhoto keeps photos in this album, if they are needed for products.