An author is a publisher of a writings, yet not all authors are writers. 
Yes they write, and yes they sell; They spend days hunched over pen or quill. To quench their thirst thus, they pour words onto paper and sell it to us. Days and years they spend hard at work to appeal their plot lines to thousands of book worms.
But that is not what it takes to be a writer.
To be a writer, you must be cruel. You have to feed readers both honey and gruel. Page by page they must be laughing and crying, through the hours hide the fact that time's flying. Writers must must be reader's puppeteers, and lead them through a world of fears. Let the creatures around become real life as you take them on a wondrous flight. Guide their every emotion, feed their every whim, in your artwork let them swim. Cause them grief with every death, make them meet your world without breath. Take them, shelter them, throw them out, your story should never be a put-out. Intertwine them with the characters they now love, watch the tears as they fall one by one. To be a writer, you must toy with emotions, take them to foreign lands without their butts leaving their cushions. To be a writer you must engulf the reader, let them drown, let them gasp, but they are only sucked deeper. 
To be a writer, you must be cruel. You have to feed readers both honey and gruel. Page by page they must be laughing and crying, through the hours hide the fact that time's flying. 
To be a writer, you must make your world real. To be a writer you must make your reader feel.
That is the difference between a craftsman and an artist.