Web design governs everything involved with the visual aesthetics and usability of a website—color scheme, layout, information flow, and everything else related to the visual aspects of the UI/UX (user interface and user experience).
Web design is concerned with what the user actually sees on their computer screen or mobile device, and less so about the mechanisms beneath the surface that make it all work. Through the use of color, images, typography and layout, they bring a digital experience to life.
Web development governs all the code that makes a website tick. It can be split into two categories—front-end and back-end. The front-end or client-side of an application is the code responsible for determining how the website will actually display the designs mocked up by a designer. The back-end or server-side of an application is responsible for managing data within the database and serving that data to the front-end to be displayed. As you may have guessed, it’s the front-end developer’s job that tends to share the most overlap with the web designer.