It seems to be roughly the equivalent of seeing a play in a theatre, compared to a seeing a film in a cinema. One has 'live' actors (usually...), the other living or long-dead actors projected onto a screen. There will come a time in the near future when the 'live' theatre performance will become holographic, too; the differences become blurred, the screen becomes the thin air on the stage. It could well become available for domestic showing, too, so one could have a 'live' holographic concert streamed onto your coffee table. You read it here first.