More often than not, these two disciplines will overlap. A web designer is usually familiar with the basic codes and a web developer is normally able to create a functional web design. It is nearly impossible for a web designer to be considered good at his or her job without understanding coding. After all, most clients want to have a "one stop" service for their website creation needs. Hence, most web designers will be able to design and code a website to function the way you want it to. This is because most websites do not require hyper-technical code. If a client wants a web site that is more advanced than your average website, a web developer is what he or she would need. Sites that require the option of user-generated content, for example, will need ways for a user to log-in, permissions to determine what the user can and cannot authorized to post or edit, etc. The same goes with e-commerce or online games. In these cases, a web designer would be out of his or her league. However, having a web designer that is able to advice on the visual elements of a page would still be highly desirable.
It would be beneficial for clients with complex requirements in website design to work with a web development company who has both designers and developers. Furthermore, if a company wants their website to be found, a digital marketing company that offers a "one-stop" shop would be ideal. These companies are capable of promoting the site, creating custom applications and integrating the website with social media management elements.