"introduction to oedipus the king": what is most likely the author's intent in writing about the difference(s) between sophocles's play and the original myth on which it's based?

The author of the introduction is probably trying to show why Oedipus the Kings is a work of literature worth reading, and what is Sophocles’ merit in writing that play.  

There is a gap of almost twenty centuries between us and Sophocles, so the introduction to the book is trying to show you why its themes are still valuable and worth reading today. It also highlights the difference between the fable of Oedipus and the way Sophocles turns it into a work of art.  

the statement that best explains why the tenth amendment reserves some rights and powers to states is that the framers believed in the principle of federalism. this principle says that some powers are in the hands of a centralized national government, while others are reserved for the governments of several states.