Difference between autopoweroff and standby in pmset
I tried to summarize all the settings in a picture.
For OS X 10.9 (it would be a little different with newer OS)
source
I would say there are just two &quot;modes&quot;: Sleep and Hibernation

Sleep: data will be kept in memory.
Hibernation: (or Standby? SafeSleep? DeepSleep?) data will kept in hard disk and requires significantly less power consumption.

Here are summaries of my understanding..

if [sleep == 0], the computer will not sleep or hibernate any more.

For notebooks, the effective setting automatically changes whenever the charger is plugged in

Normally, sleep minutes are simply equal to displaysleep minutes, which you can set in System Preferences &gt; Energy Saver
But under the Power Adapter tab, checking &quot;Prevent computer from sleeping automatically when the display is off&quot; will override sleep minutes to 0




if [standby == 1] and [hibernatemode == 3], the computer will wait another [standbydelay] seconds before really entering hibernation.
[autopoweroff] is just an extra implementation to fulfill regulatory requirement and has the same impact equivalent to 2)
either 2) or 3) takes effect if one of them is reached at first.
if [standby == 1] and [hibernatemode == 25], the computer will enter hibernation immediately after [sleep] minutes.

Note:  in MacOS 10.13 autopoweroffdelay specifies the delay, in seconds, before entering autopoweroff mode.
Can someone review and confirm the interpretation?? thanks