Author and writer are most times thought to be the same, but the truth is both words are not the same. An author is a word used to describe someone who originates or creates a work, especially when it comes to literary composition.
This word is mostly used as a title for people who write books for a living. A writer, on the other hand, is used to describe someone who produces or writes literary works. A single person can hold the two titles.
For example, if you are the originator of a literary work, that makes you become an author, but you can also become a writer if you wish to write everything by yourself. A perfect example of this is autobiographies. A writer can just be anybody as far as their writing skills are impeccable, an author is not just a title that can be given to anybody; you must have total rights to all your published literary works.