That was the question posted at Tiny-Lights.com on the Searchlights and Signal Flares page; I missed the deadline (March 13th) to post an answer back to them. But it is a good q. So I'll answer it here.
An author or writer? At this point I'd settle to be considered either one, really. But upon reflection I'd say , that a writer is someone who practices the word-craft of writing, whether it be for their own work (novel, memoir, poems) or on behalf of another such as a newsletter, an indigent and lazy relative or writing a manual for a corporation or business. An author would be along the lines of the French auteur, a creator of a piece or body of work. The author, who could also be a writer, is promoting their personal vision in some way; only they could have created that work. The writer is a skilled artisan who builds for themself and others, creating work that another skilled craftsman could as handily do, though of course issues of quality/approach might come up.
So I think most of us are both, all rolled up in one tidy (or untidy, in my case) package. The writer in service to the author; the author driving the writer. As illustrated when my friend Ruth greeted me "Hey, here's our author" when I came into her office the other day. I turned halfway around to see who this Arthur was. "No, you, silly, you're the author." That pleased me; I had thought I was writing the essay for the newsletter, but I saw immediately that I'd also authored it. While another writer could have written a piece about the program, no one else would have written the mini-essay that I had.
It's possible that tomorrow I might post a different opinion. But no matter what, next month I'm going to get my rusty butt in gear and reply to this prompt:
What story are you being asked to tell? (deadline: 04/15/08)
find it at http://www.tiny-lights.com/searchlights.html