Anna176942, I'm far from a native speaker and am basing my comment upon reading examples on Glosbe -- which has been dissed occasionally by the moderators here. (Even so, I like Glosbe for the contextual examples offered, even if, once in a while, they may include a bungled translation.)
My impression is that οροφή can mean either "roof" or "ceiling," (and "ceiling" in both physical and metaphorical uses). Σκεπή seems to be used mainly for a physical roof. And a third term, στέγη, can be either a physical roof or a metaphorical one, meaning "shelter."
Maybe one of the moderators will be able to add to or modify some of this.... Best wishes, Paul