The two images below both are good examples of what I am trying to say. They are both of the same place but to look at them you couldent tell it. The one on the left is just a rough sketch. Some artists do rough sketches and go back and fill in the details later. The one on the right is a final draft. If you look at the one on the left you can see that its not all that detailed. It looks rather two dimentional whereas the one on the right is very detailed. It almost looks like you could jump right in and be there. That is the difference between shape and form. Form is depth. Depth is achieved by adding value, texture and color to shapes and lines. If done correctley this will offer a design that also fulfills all of the Principles of design.