There should be a better understanding of what clients want before they order so they can use the right language. Copy is an advertising term for prose that sells or persuades, appeals and charms. it is not heavily researched geographically specific real estate data. Articles are formal essays following established traditions of writing. There is an introductory paragraph, a development of the thesis, and several paragraphs expanding and explaining that detail. Essays come form the french verb essayer, to try. Try to explain, ilustrate, flesh out, demonstrate. Hiring a copy-writer and expecting essays is wrong. Ordering articles on no specific detail when you want specific information is wrong. In my experience clients readily expect one when getting the other.
That's always been a problem with clients and I notice a lot of writers can't tell the difference either.
This is why it is important, as a writer, to make sure that you know exactly what your client wants. No client is going to take a job from you because you take a minute to clarify his or her needs and most appreciate that you are taking the extra time to make sure that you understand what is expected. Why not, instead of getting frustrated with your clients and possibly end up delivering something that he or she does not want (which wastes everyone's time) say "so what do you hope to accomplish from these articles?" or even "when I hear the words "web copy" I think of [insert your own definition here]. Is that what you want?" (I actually got a raise on a job this morning because I took the time to tell my client that what he was describing were actually articles, not landing pages.)