Web design encompasses many different skills and disciplines in the production and maintenance of websites. The different areas of web design include web graphic design.
Mobile UX design is the design of user experiences for hand-held and wearable devices. Designers create solutions (typically applications) to meet mobile users' unique requirements and restrictions.
Web development is the work involved in developing a Web site for the Internet or an intranet. Web development can range from developing a simple single static page of plain text to complex Web-based Internet applications.
App design encompasses both the user interface (UI) and user experience (UX). Designers are responsible for the overall style of the app, including things like the color scheme, font selection.
A WordPress developer is one who can make custom plugins and modules for WordPress. WordPress designer (a true one) is able to develop a theme around WordPress.
Search engine optimization is the process of improving the quality and quantity of website traffic to a website or a web page from search engines.