Hibernate is a feature in Windows which allows you to save all the current state of your Windows in switched on condition to your RAM. This means ifd you hibernate your PC and again switch on all apps and Windows will start in same state when you switched it off. Also It takes very less time for Windows to resume from Hibernate state.
Remeber Hibernation requires memory space equal to your RAM size on harddisk through file C:\hiberfil.sys (hidden file).
A power scheme is a set of rules that tell after what time various devices go into a power down mode , it also tells which all devices can get a system out of a power down mode.