This is a great graphic, but honestly I have been asked this question many times. I currently work as a Web Developer but my title is Web Designer. Partly because even the company I work for is not clear on the distinction. The truth is that the line is fine and varies greatly from Weby to Weby. I actually would take it a step farther and call my self a scripter as a-posed to a coder. Not that web designers can’t be coders or vice versa.
As a general rule a web designer designs and builds web sites. Online presences or brochures or installs open source softwares like blogs and stores. A Web Developer creates these softwares. I am a web developer because I am part of a team of people developing software that runs on the internet. You don’t have to install it for it to work, you just need a modern browser and an internet connection. My part on this web development team is the part of the designer/scripter.
So what is the difference between scripter and coder? Thats a subject for another time.