Copy writing used to be something you did to please the Creative Director. It was punchy or pithy or pathos, whatever the client needed, or thought they needed, and there was no way to know if what you were writing was reaching the audience.
Now we write specifically to attract a target. Messaging about addiction, or immunization, or a town, or upholstery, or cabinet making, sporting goods, or antiques. The words can be in a targeted email or an online form. They can even be embedded as meta tags, unseen by any but the Googlebot!
Writing can also be medical writing, technical writing, or grant and proposal writing. The key to all writing is organization, grammar, spelling, style, and organization - yes, it is in there twice intentionally!