The Real World
Their world is much like ours with a few notable exceptions.
Their world is much more technologically advanced. (More along the lines of I, Robot or Star Wars.)
They have a significantly smaller population. (Approximately one billion people spread across the surface of their world.)
Due to these two factors, they also have less problems with pollution, but they also tend to be more "green" in everything they do.
But the most important difference is their "dream-time". This is when they communicate as muses to their creators (Harry Potter to JK Rowling, Obi-Wan Kenobi to George Lucas, etc) and it is during this time that they also communicate as muses to others within their universe (Obi-Wan with Qui-Gon, Harry with Ron, etc). Upon waking, they are completely cognizant of what happened as their muse-selves. However, because there is so much material that doesn't make it into canon, more can happen in this dream state than what happens in canon, so long as it does not directly contradict canon sources.
Like our world, they have one sun, one moon, and several continents that cover a wide range of landscapes and terrains.
Also, like us, they have criminals which are free to be played. Criminals can directly access the same dream state as everyone else, but keep in mind, they are also subject to the same laws as everyone else.