Think of it in this way; a circuit structure is any sort of diagram which illustrates how a circuit operates where the primary purpose is the proper wiring of components and their relationship to each other instead of physical location relative to each other or planning prototypes. Nevertheless, in some applications classifying diagrams can be challenging so consider this as overall information. I have found this is particularly true when dealing with much more complex circuits and electronics. I'm likely to work with a simpler but average industrial circuit because these circuit set ups are the exact same, but yet where you can observe how each sort of diagram shows the function of the circuit in their own manners.
Right, much less mess? I have enough info in each one these diagrams to know exactly what this circuit will do and also where to start looking for problems. Hope this helps. ( Note: do not confuse circuit or schematic diagrams together with wiring diagrams; wiring diagrams will often demonstrate pictures of components like the pictorial, and how the entire or part of a circuit has been wired. The difference is that wiring diagrams usually place an emphasis on actual physical location of necessary elements relative to each individual that essentially tell a layman exactly what to do concerning the wiring)
A design diagram refers to a particular type of circuit structure that uses standard electrical/electronic symbols rather than images to show the way the circuit (or portion of it) functions. Below is a normal 3-wire motor controller circuit employing a normal short stop stop - start pushbutton channel using a schematic diagram. (Momentary this means the button/switch you activate will return to its default position once you let go of this, typically by a spring which forces the button/switch to get this done.)
Here's another schematic diagram demonstrating the identical circuit, components and connections and it looks different but they both fall into exactly the identical category.
Pictorial schematic diagrams, or pictorial circuit diagrams are essentially the identical thing with the identical purpose, but they use images of elements within the circuit instead of symbols. Again, here's the identical exact circuit (virtually except a controller was included and they are utilizing conductors L1 and L3 instead of L1 and L2.
Here is a variant of a schematic diagram known as a ladder diagram. The main aim of this diagram is to demonstrate the logic (speaking to electrical management ) of a circuit board. This diagram is the one that I mostly come across in my own line of work, and it's very effective for troubleshooting issues or learning the way the circuit functions. Some circuits are so enormous that many kinds of schematic diagrams need to be read in increments in book form (generally with coded numbers so info can be easier found). Again, here's the exact same exact circuit since the first 2, however, considering it in ladder shape.