[Lucid:]

the difference is that Hogwarts houses are completely different from locker numbers. they determine your entire social life and living conditions. also, since houses are determined by character traits, it's a very personal and defining piece of the world she wrote.
I suppose it's more similar to us on Trisphee, talking about, "If I lived in the Trisphee universe, what race would I be? Which planet would I live on?"