SafeSleepOnce puts your Mac into safe sleep once and automatically enables normal sleep afterwards.
SafeSleepOnce puts your Mac into safe sleep once and automatically enables normal sleep afterwards.
Safe sleep is also called deep sleep, hibernation or suspend-to-disk, whereas normal sleep is also called standby or suspend-to-RAM.
To make a long story short:
Normal sleep is fast but uses battery since your memory is not shut down. The LED indicating that your Mac is sleeping is on.
Safe sleep is slow but does not use any battery since your memory is shut down too. The LED indicating that your Mac is sleeping is off.