Dictionaries have a broad definition of "screen" because it is used broadly in English...
3.
a. A surface, as on a smartphone, television, or computer monitor, on which one can read and view electronically displayed information and images.
b. A surface on which text and images are projected for display.
c. The medium in which movies are shown: a star of stage and screen.
Thus, any surface can be called a 'screen' if there's a projection onto it.
Of course, some people mean a sheet of some material, rigid or non-rigid, that is particularly made for projections.
And when people have different definitions of 'screen,' then they will disagree what is or is not a 'screen.'
So, avoid saying "screen", what is the nature of the surface onto which the projection of 'space' is being projected onto? Is it just a wall? Painted black? A silver stretched sheet of nylon, plastic? Is it (semi-transparent)? Is the projection on the front or from behind?
