A little about Form, Stucture and Content...

Form - Form is how you as a photographer would manipulate the image and the objects in the pictures shape to impress an idea or theme onto the picture, This can include
Line
Shape
Space
Value
Texture
Colour
Tone
Quality Of Light
Framing.

Structure - Structure is the arrangement and relationships between content and form to creat deeper meanings to the picture. These meanings are often open to interpretation, because each different person could see different sides to the theme due to their own experience of the issue. An example of form working to create structure could be something like lots of bold lines used to show conformity.

Content - Content is the objects in the picture and how they are presented to the audience, These often tell the obvious about the stucture or themes of the picture, they are what they are, when you start to go deeper into the meanings of the content you are starting to comment on the themes and structure.