Mobile development involves creating software applications that are specifically designed to run on mobile devices, such as smartphones and tablets. These applications can be native, meaning they are built using the programming languages and tools specific to the device's operating system (e.g., Swift for iOS, Java for Android), or they can be web-based, meaning they are accessed through a web browser on the device.

Web development, on the other hand, involves creating and maintaining websites and web applications that can be accessed via a web browser on any device. This can include everything from the design and layout of the website, to the development of back-end systems and databases to store and manage data. Web developers often use a variety of programming languages and tools, such as HTML, CSS, JavaScript, and PHP, to build and maintain websites and web applications.