What is the difference between putting a PC to sleep and putting it in hibernate?

My unknowledgeable explanation:

It was explained to me that hibernate shuts down everything except for chips that have their own power supply (to keep a clock running), while sleep closes all active programs and some of the programs that run in background

Great question! I never knew, I usually put mine in sleep mode.
Does hibernate mode add to your PCs longevity maybe?

Here is Microsoft’s definition:
http://windows.microsoft.com/en-us/windows7/sleep-and-hibernation-frequently-asked-questions

Sleep: turns off most chips, but keeps power to the RAM so that you don’t lose data.

Hibernate: saves all data from RAM into hard drive. Turns off almost all chips (including RAM)

If you put a PC to sleep in turns off completely shutting all the windows down. But if you put a PC in hibernate mode then it keeps the windows open the screen just goes black and the computer semi shuts off.

@Zm1l3y that is the opposite of true.

So, the difference has to do with your RAM, mostly. RAM is known as ‘volatile memory’, which means that it can be accessed and changed very fast, but as soon as you cut the power all the data is lost. Your hard disk, on the other hand, is non-volatile; if power is cut, the magnetization on your disks is just fine, but reading and writing is slower. So, this leads to the three types of ‘shutdown’:

Sleep: hard disks and cpu shuts down, but power to the RAM is preserved. This means most of the operating system info, as well as any programs you’re using, is maintained, so it continues to draw power but recovery is very fast.

Hibernate: Like sleep, but in order to save power, the contents of your RAM is saved to the hard disk. This takes some time (hence the saving and loading screens typically seen), but is less power intensive since now the computer can be totally shut down, yet returned to the exact state it was in once the data from the disk is loaded back into the RAM.

Shut Down: In this case, everything going on is stopped, the operating system shuts itself down, and the computer is ‘totally’ off (not quite, there’s always something drawing power, but not much). This allows for any running errors to be gotten rid of, programs to update themselves that may need shut down to do so, etc, but takes the longest time since everything then needs to be turned back on and loaded back onto the RAM.