Think of it in this way; a circuit structure is any sort of diagram that demonstrates the way the circuit operates where the most important goal is that the appropriate wiring of elements and their relationship to each other instead of physical place relative to one another or intending prototypes. However, in some applications classifying diagrams can be difficult so consider this as general advice. I've discovered this is especially true when working with more complicated circuits and electronic equipment. I'm likely to work with a simpler but typical industrial circuit since these circuit set ups are the exact same, but yet where it is possible to observe how each sort of diagram shows the function of the circuit in their own ways.
Pictorial design diagrams, or graphic circuit diagrams are essentially the exact same thing with the exact identical function, however they use images of components inside the circuit rather than symbols. Again, here's the exact specific circuit (almost except a control transformer was added and they're using conductors L1 and L3 rather than L1 and L2.
Here is another schematic diagram showing the identical circuit, components and connections and it appears different but they both fall into exactly the same category.
Following is a variant of a diagram known as a ladder design. The primary goal of this diagram will be to show the logic (speaking to electrical management ) of a circuit board. This diagram is the one that I mainly come across in my own line of work, and it's extremely effective for troubleshooting issues or learning the way the circuit works. Some circuits are so huge that many types of schematic diagrams need to be recorded in increments from novel form (usually with coded numbers so info can be easier found). Again, here's the same exact circuit as the first two, but looking at it in ladder form.
Much less mess, right? I've got enough information in every one these diagrams to know just what this circuit does and also where to start looking for problems. Hope that this helps. ( Note: do not confuse circuit or schematic diagrams together with wiring diagrams; wiring diagrams will often demonstrate pictures of elements like the pictorial, and also how the whole or portion of a circuit will be wired. The difference is that wiring diagrams generally place an emphasis on real physical location of necessary elements relative to each other that basically tell a layman Just What to do concerning the wiring)
A design diagram refers to a specific kind of circuit diagram which uses standard electrical/electronic symbols instead of images to show the way the circuit (or a part of it) works. Below is a normal 3-wire motor controller circuit employing a typical short stop stop - start pushbutton channel utilizing a schematic diagram. (Momentary here means that the button/switch you trigger will go back to its default position once you physically let go of it, typically by a spring which forces the button/switch to get this done.)