Sleep saves
any open documents and programs to RAM, switches off everything else, and then
places the computer in a low-power state (commonly known as standby-mode), for
this reason the computer can ‘wake-up’ very quickly. In Sleep mode, the power load is reduced considerably, saving a lot of
energy. However, the power must not be cut off, and must be continue to supply
to the computer. If you lose power while in sleep state, all current data will
be lost since RAM is what we call volatile memory, so if a PC loses power, RAM
loses the information it has stored in it.
Hibernation
saves any open documents and programs to a hard drive before removing power
from the computer. When computer is turned back on the running programs are
reloaded from the file stored on hard drive so it appears they were never exit.
The PC consumes even less power when it’s switched to hibernate. In fact,
during hibernation, no power at all is used; you could technically leave the
computer in this state for years. The main disadvantage of hibernation is that
the computer takes longer to switch itself back to working state than it would
from ‘sleep’.
Both
‘sleep’ and ‘hibernate’ are power saving features that provide an easy and
quick way to leave your computer in existing last state and come back to work
on it at exactly the same state later without waiting too long to system to
restore itself.