What is the difference between a screen and a monitor?

I am having an issue when trying to set up 4 monitors for an experiment that I am running using psychopy. I need to show a stimulus (right now just a grey screen, but will eventually be a more complicated stimulus) on 4 different monitors.
The first problem I am facing is I cannot seem to present the stimulus on the different monitors at the same time.
the second problem I am facing is that some of the monitors have different dimensions (when presenting an object, one monitor shows a blown up version of it than another)
I cannot seem to affect anything in Monitor Center because these screens seem to be under one ‘monitor’.

Please help THANK YOU!