Arnold Palmer once said,
There is a difference between a golfer and someone who plays golf.
It sounds like pedantic semantics (say that ten times fast!) but there is a fundamental change that occurs when you go from doing to being.
The boundary between being a writer and someone who merely writes is hard to define, but it can be recognized by a few different characteristics. The most obvious difference is a writer gets paid to do so, and probably — hopefully — makes a living doing it, although there are a great many successful, published writers that hold down full-time day jobs to pay the rent despite having one or more books on the shelves. Someone who writes probably isn’t cashing very many royalty checks or buying second homes with the advance on their next novel.
Money isn’t everything. Where the financial side of writing ends, the matter of attitude picks up and this is probably where writers separate themselves from the rest of those who merely write. Let’s say you are attending a cocktail party and someone asks, “So, what do you do?” Your answer will say it all. “I am a writer.” Or is it something more like, “I sell insurance,” followed 10 minutes later, buried in the midst of idle chit-chat, “In addition to being a soccer Mom, I’m also writing a novel.”
This brings up another point of contention when defining what constitutes a writer vs. someone who merely writes: have you been published? Some, perhaps many, would argue that you cannot call yourself a writer until you’ve been published. “I’m writing a novel” doesn’t cut it. “I just published my novel,” does. No one cares what you’re going to do, only what you’ve already done. It’s sad, but many people feel that way. There are exceptions, however; see the previous paragraph regarding attitude.
The significance of labels only matter so much, however. It doesn’t matter if you’ve yet to be published, and it doesn’t matter if your works don’t earn you a six-figure annual income. If you have the drive to write, if putting words to paper is your passion and is your default activity — it’s what you’d rather do than anything else, then you may be a writer after all.