The outside world may not care about such definitions, but as self-publishing became ever cheaper and easier over the past 15 years (due to print-on-demand, distributing those POD books via Amazon, and finally Kindle ebooks), writers have hotly debated who is a professional.
Only professional authors are permitted to join many writers' organizations, so defining a professional is not an entirely fanciful past-time. It has real world consequences.
Richard Lea observes, in Britain's The Guardian newspaper [January 23, 2014], that most self-published authors not only don't earn much money from their books -- they also don't think it's relevant to defining a writer.
I found this excerpt especially interesting:
[T]he self-publishing revolution has allowed "hundreds of thousands of voracious readers with a dream of writing a novel" to write books "out of love and passion, just like a kid goes out and dribbles a basketball for hours every day or kicks a soccer ball against a garage wall". But over the past few decades we wouldn't have called these people "writers" any more than we would call that kid in the back yard a footballer. If all it takes to be a writer is to stick your work online then we're all writers now.
In the old days things were much clearer. All you had to do to call yourself a writer was publish a book, which meant you needed someone else to publish it – and someone else to buy it.
Read the full story here.