Is my impression right that in some airports, the monitors show the flight as boarding at the boarding time, regardless of whether it is actually boarding or not (assumin that no significant delay has been announced) while in other places, boarding really means that it's boarding?

I'm not going to get started on my usual rant about AMS boarding meaning that passengers are admitted to a holding pen with no facilities in order to have the privilege of fighting for seats and electrical outlets and later to board in one big mess. It's more like gate goats than gate lice.