If this is an attempt to define...
So.... if writers are authors of fiction, then journalists are not writers. (Or shouldn't be in their day job.)
But, if writers are people who creatively put words together to promote understanding and/or enjoyment than journalists are unequivocally writers.
I'm afraid we wont get too far with definition until we have a lengthy discussion.
Being a writer doesn't necessitate creativity for enjoyment although it would be recommended that they do promote understanding.
There a plenty of writers who write technical material- manuals; scientific papers; journals; reviews and the list goes on and on(sometime but not always entertaining as much as informative-in fact often when attempting to make them too entertaining they distract from the message).
I'm sure if we pull out dictionaries and start making a list of definitions we might have something to start with.
It might take further time to come to a consensus of which parts to cherry pick or if we should include the entire definition.
writ·er /ˈrīdər/
noun
noun: writer; plural noun: writers
a person who has written a particular text.
"the writer of the letter"
a person who writes books, stories, or articles as a job or regular occupation.
"the distinguished travel writer Freya Stark"
a person who writes in a specified way.
"Dickens was a prolific writer"
a composer of musical works.
"a writer of military music"
Computing
a device that writes data to a storage medium.
Stock Market
a broker who makes an option available for purchase or sells options.
a person who has a specified kind of handwriting.
"neat writers"
historical•British
a scribe.
archaic•British
a clerk, especially in the navy or other government offices.
au·thor /ˈôTHər/
noun
noun: author; plural noun: authors
a writer of a book, article, or report.
"he is the author of several books on the subject"
someone who writes books as a profession.
"my favorite authors are Kurt Vonnegut and Aldous Huxley"
the writings of a professional author.
"I had to read authors I disliked"
an originator or creator of something, especially a plan or idea.
"the authors of the peace plan"
verb
verb: author; 3rd person present: authors; past tense: authored; past participle: authored; gerund or present participle: authoring
be the author of (a book or piece of writing).
"she has authored several articles on wildlife"
be the originator of; create.
"the concept has been authored largely by insurance companies"