What is the difference between standby and suspend-to-disk?
Standby mode saves whatever you were doing to the laptop’s RAM chips, and thus requires a steady, but minimal, source of power. A tap on the keyboard wakes it up, and this happens almost instantaneouly. Suspend-to-disk (also called S2D or hibernation mode) saves whatever you were doing to the laptop’s hard drive, and thus does not require power (it shuts off the laptop). Turning on the power switch revives it, and this usually takes about a minute (including boot-up time). Waking up from S2D is about 30 seconds faster than booting up from a normal shutdown. If you want to save power and like quick boot times, suspend-to-disk is the way to go.
