Think of it this way; a circuit structure is any kind of diagram that demonstrates how a circuit operates where the major objective is that the proper wiring of elements and their connection to each other instead of physical place relative to each other or intending prototypes. However, in some applications classifying diagrams can be challenging so choose this as general advice. I've discovered this is particularly true when dealing with more complicated circuits and electronic equipment. I'm likely to use a more straightforward but typical industrial circuit since these circuit setups are the exact same, but where it is possible to observe how each type of diagram shows the operation of the circuit in their own manners.
A schematic diagram refers to a particular kind of circuit design that uses standard electrical/electronic symbols instead of images to demonstrate the way the circuit (or part of it) works. Below is a normal 3-wire motor controller circuit employing a typical momentary halt - start pushbutton station employing a schematic diagram. (Momentary this means that the button/switch you trigger will go back to its default location once you physically let go of this, typically by a spring which forces the button/switch to do this.)
Following is a specialized variant of a diagram. The principal goal of this diagram will be to demonstrate the logic (speaking to electrical management ) of a circuit board. This really is the one that I mainly come across in my own line of work, and it is extremely effective for troubleshooting problems or learning how a circuit works. Some circuits are so huge that most types of schematic diagrams need to be read in increments from novel form (generally with coded numbers so that info can be easier found). Again, here is the exact same exact circuit since the first two, however looking at it in ladder shape.
Right, Less mess? I have enough information in each one these diagrams to know precisely what this circuit does and where to start looking for problems. Hope that this helps. ( Note: do not confuse lecture or circuit diagrams together with wiring diagrams; wiring diagrams will often demonstrate images of components like the pictorial, and how the whole or part of a circuit will be wired. The distinction is that wiring diagrams usually put an emphasis on real physical place of necessary components relative to each other that basically tell a layman Just What to do about the wiring)
Here is another schematic diagram showing precisely exactly the identical circuit, connections and components and it looks different but they fall into precisely exactly the same category.
Pictorial schematic diagrams, or graphic circuit diagrams are essentially the exact same thing with exactly the same purpose, however they use pictures of elements inside the circuit instead of symbols. Again, here's the identical specific circuit (virtually except a control transformer was included and they are using conductors L1 and L3 rather than L1 and L2.