It will work either way, there is no polarity when a circuit is made.
There is polarity before a circuit is made. One wire is live, one wire is a neutral return.
For a basic heater, plugged in one way will have the heating element always live, and the other way it will only be live when it is switched on and a circuit is made.
With single phase AC there is no polarity, when you plug something in you don’t need to know which plug is live, it will work either way.
It will work either way, there is no polarity when a circuit is made.
There is polarity before a circuit is made. One wire is live, one wire is a neutral return.
For a basic heater, plugged in one way will have the heating element always live, and the other way it will only be live when it is switched on and a circuit is made.
One is definitely safer than the other.
Almost all devices that switch mains power, have both the live and neutral connected to the switch.
Almost…