When you wake a Mac from hibernation, RAM got written to disk and power removed from memory. Then, at wake, it gets read back into RAM. This takes longer than normal, or standby sleep (depending on the delay set) and is visible at wake time by showing an Apple symbol and progress bar underneath (white time markers filling up).
Also running the following command in Terminal:
pmset -g log | grep -i "wake from"
will show the sleep states, e.g.
Wake from Hibernate
Wake from Normal Sleep
Wake from Standby
The last time I saw the 'Deepsleep' widget in action, it did the same as hibernation, i.e. write to disk and remove power from memory.
As the man pages (
man pmset) hint in the quote below,
autopoweroff should be set to the value "0", via the same
pmset command you've used to set hibernatemode, to set your MacBook Pro to use hibernation instead of normal, or standby sleep (I would also disable any Energy Saver System Preferences to wake your Mac periodically):
For example, on desktops that support standby a hibernation image
will be written after the specified standbydelay time. To disable
hibernation images completely, ensure hibernatemode standby and
autopoweroff are all set to 0.
PPS. But please also consider the following thread here on AskDifferent:
How to add hibernate mode to MacBook Pro