You ask an intelligent question. In standby condition, the computer uses less energy whereas when you shut down or restarting the computer, a little more energy is required to do it. Because, during the shutdown, the computer needs maximum RAM resources to close the startup applications and then follow the shutdown procedure. Therefore, there will be a need for more energy use for conducting this procedure. The same steps also require from the restarting the computer. However, in a standby condition, the computer just stops the screen display but it will not stop completely the running applications. Moreover, it will save the computer power energy.