Web Development encompasses all the tasks required to bring a web site to the internet, whereas Web Design refers only to graphic design. A typical web development process at The Kilbot Factory would involve site planning, wireframe creation, web design, coding, search engine optimisation, and after release; site maintenance and advertising. The Web Design component would be handled by a web designer, usually someone contracted especially for the job based on the design goals of the client.
The role of the web developer will vary from agency to agency and from project to project. Most commonly, the web developer refers to the person responsible for the code component of the development process. In a small web development agency, a web developer may be responsible for all aspects of development, including design. Indeed, a good developer should have experience in all aspects of the development process so that good practices are built into the web site as a matter of course.
As the internet industry matures there is a need for more specialised roles in web development. Large agencies will usually include a project manager who takes care of the site planning, wireframing and manages the web developers and web designers. Specialist SEO firms are springing up all over the internet (although most of them are charlatans in this humble web developers opinion :p ). Web developers themselves will usually pick one or two languages to specialise in.
For more information about my specialities, please visit the About page.