Honestly, I have no idea how one should define a writer. Does the act of writing an essay make one a writer? Technically, from the roots of the word and the way my strange logic interprets it, a writer is just a person who writes anything. However, people do not usually call the child writing his homework an essay. Rather, people associate a writer with telling a story, but even then, there are distinctions. People who tell a story through a poem are called poets, yet they too, are writers, because they are also playing with the same tool as a writer. Maybe they are not using the same expressions, but regardless of that fact, the object in their hand remains the same, a quill that is designed to leave words behind that stay with us for a long time.
Maybe that is what defines being a writer; creating a story which withstands the sand of time. Maybe being a writer is just as simple as putting one's thoughts into words on paper. Maybe being a writer means using a certain kind of format to tell the stories one can tell. There are just so many ways to be a writer that it would be impossible to list them all, so I am not even going to bother. But there is one thing for certain, and that is, that being a writer is a subjective thing. The favourite writer of a person may be considered the bane of all books by another, or a writer may not be recognised in certain circles despite their clearly staggering achievements. Therefore, it is troublesome to define what makes us writers, it is bordlerline impossible to tell where the thin line lies between a person who writes and a true writer.
I think that an easy way to define being a writer would be the following: "A writer has the ability to put their freely flowing creativity and imagination into terms that others can enjoy and understand." That is only my opinion of course, and I think that every single human being on this planet has a different definition of just what is fitting of a writer.