Writing is an activity that write some characters for non online business, while ghostwriting is for online
In our context, there is probably none. The term ghostwriter had been in use for over a century : A ghostwriter is a professional writer who is paid to write books, articles, stories, reports, or other texts that are officially credited to another person. Celebrities, executives, and political leaders often hire ghostwriters to draft or edit autobiographies, magazine articles, or other written material. ( http://en.wikipedia.org/wiki/Ghostwriter )So, if you plan to sign the article with your name, you hire a ghostwriter.I all other cases, it's a writer, and using the term ghostwriter only makes it look more interesting...Both are the same person.
However, all of us could be ghostwriters now either, because all of us write online using nicknames. There are just a few people who use their real names online.
I've always understood Ghostwriting to be someone who is paid in order to write on behalf of someone else. The work is then credited to someone other than the actual other. Most writing jobs online are ghostwriting jobs because you give up rights to the content.
There are those who do their own writing and there are those who are not skilled in that area or lack the time and may choose to hire a ghostwriter. They are hired to write books, novels, articles, letters... on behalf of their customer who then takes the credit as the writer. At times, a ghostwriter may be given credit as co-author or thanked under acknowledgements. They may even be required to sign contracts that obliges them to not reveal themselves.
Nine times out of ten, celebrities use ghostwriters when they want to write a book. Overall, a ghostwriter is ideal when a person lacks the patience or skill to write for themselves. Ghostwriting is one of the most profitable niches in writing.