Web design is the customer-facing part of the website. A web designer is concerned with how a site looks and how the customers interact with it. Good web designers know how to put together the principles of design to create a site that looks great. They also understand about usability and how to create a site that customers want to navigate around in because it’s so easy to do.
Web development is the back-end of the website, the programming and interactions on the pages.
A web designer:
Focuses on look and feel of a website
Is competent in color scheming, graphic design, and information flow
Creates a great user experience
Is right-brained: Strong intuition, creativity, & imagination
Portfolio is worth more than a degree
A web developer:
Creates the inner workings of a website
Is competent in programming languages (PHP, .NET, Python, C, Ruby)
Develops the user interface
Is left-brained: logic, linear thinking, technical
Hands-on coding experience is required (either your own products or github)