The main distinction between a native app and a web app lies in how they are built and accessed. A native app is specifically designed for a particular platform, such as iOS or Android, using platform-specific programming languages. These apps are downloaded from app stores and offer better performance and access to device features. In contrast, web apps are accessed through a web browser and built using standard web technologies like HTML, CSS, and JavaScript. While web apps are generally easier to deploy and maintain, native apps provide enhanced user experiences and functionality.