what's the difference between shut down with the start button upper keyboard (red light) and using the menu and choosing shut down ?
The first method is fastest...
As far as I know, for most computers nowadays there is no difference. On some computers you can find settings telling it what to do (hybernate/sleep/shut down etc.) when you push the power button. I don't have mine yet though so I can't say for sure; but there's likely no difference.
tks for your response
Rectification for may first post : it's not red light but green led on the button.
it seems that with this button the procedure of extinction is different on the screen, and it's take less time to shut down for sure. No menu in the bios to precise the way of extinction with this button sleep or log out or shut down)
Well if it's going through some sort of shut down process I'm sure it's fine. Just as long as it's not immediately cutting the power or anything like that.
I guess the behaviour depends on the system installed and the settings you choose. On my Xubuntu distro (xfce4), I seem to remember you could set this in the system settings. Probably works the same in other Linux distros.
When/if the machine freezes and you need to switch it off "by force", you can press and hold the power button for a few seconds.
In 3 days, a completely turned off laptop discharges by 6%