The arched condition with the doors permits more substantial openings, which may be handy in structures like barns or garages. So the kind of roof enclosing the volume dictates the shape of the gable. A gable wall or gable stop much more normally refers to the entire wall, such as https://share.evernote.com/note/baeb7a9b-5771-3ea9-bb5a-265263b499c9