Circuit diagrams show how electronic components are connected together. Each component is represented by a symbol and a few are shown here:
Circuit diagrams and component layouts
Circuit diagrams show the connections as clearly as possible with all wires drawn neatly as straight lines. The actual layout of the components is usually quite different from the circuit diagram and this can be confusing for the beginner. The secret is to concentrate on the connections, not the actual positions of components.
The circuit diagram and stripboard layout for the Adjustable Timer project are shown here so you can see the difference.
A circuit diagram is useful when testing a circuit and for understanding how it works. This is why the instructions for projects include a circuit diagram as well as the stripboard or printed circuit board layout which you need to build the circuit.
source: http://www.kpsec.freeuk.com/study.htm
