As the files have been moved to the hard drive, the System will take a little extra time to boot on than required by Sleep. When in an extended sleep, your computer automatically transfers the state of your files to the hard disk drive and switches to Hibernation. This is made possible by storing the current state of the files in the hard drive instead of the temporary memory. Unlike Sleep, which stores files in the RAM and therefore requires a constant power supply, Hibernation doesn’t require any power (like when your System is shut down).
Hibernation, pretty much like Sleep, also saves the state of your files & applications and is activated after your System has been under Sleep for a prolonged period. The screen boots on within a few seconds, and all your files & applications will be in the same state as they were when you left. You can get back to work by a single click of the keyboard or by simply moving your mouse. This allows the System to be in a low-power state but still be running.
In the sleep state, the screen is turned off, and all the foreground processes (files and applications) are saved in the memory ( RAM). The sleep mode is activated by default when you leave your computer without shutting it down. It differs from Sleep in terms of power usage and where your currently open (before you left your System) files are saved. Hibernation is a power-saving state primarily made for laptops, although it is available on certain computers as well.