When you shut down your computer, you turn everything off. All of your applications, windows and documents have to be closed. Starting up your computer again can take some time. And then you have to reopen everything you want to use.
To save time, you can use Hibernate or Sleep. Both of these save the exact state of your computer. You don’t have to close anything. All your windows, programs and documents are stored as-is.
When you start up the computer, everything is restored. All your windows are just as you left time. They’re even in the same place on your desktop. And you can pick up right where you left off.
They both still seem the same, don’t they? But each offers a different level of power saving and convenience.
When using Sleep, your computer’s state is stored in RAM. The display is turned off. Your hard drive is stopped. And other components are shut down. But a minimal amount of power is still applied to the RAM. This allows the RAM to hold on to your computer’s state.