What is the difference between hybernation and sleep mode

In standyby or sleep mode, the power to the hard drives, fans, monitor etc is shut off, which gives you instant dramatic power savings if you are using a portable device with a battery as a power source, however the computer still uses a little bit of power to keep its RAM (volatile Random Access Memory) powered. When you resume from the standby or sleep mode, all your documents, programs etc that were open come back to life instantly as you left them running. The downside is that your computer still uses 2% of the battery power to maintain power to the RAM, which over longer periods of time can drain your battery.

In Hibernation mode, you get the benefits of preserving the state of your running programs and open documents as well; in this case the computer swaps the contents of computer memory (RAM) to the hard drive and completely shuts down power. When you want to resume from hibernation the computer essentially loads everything back into the RAM from the hard drive, once complete you find your programs and documents in the state you left them in. The advantage of hibernating is that it does not waste any battery power but the downside is that it takes longer to resume because everything has to be swapped from the hard drive back into the RAM.

In both scenarios, you avoid going through the complete Windows boot cycle, logging on process and then opening up your programs and work.