What is the primary distinction between screen and block design?

The primary distinction between screen and block design lies in the functionality that each element provides in a mobile application. Blocks are designed to be reusable components that encapsulate specific functionality or a set of visual elements, and they can indeed have output parameters to pass data back to screens or other components within the application.

However, screens, which are the primary units for user interaction, typically do not have output parameters because they are the endpoints for user interactions and are designed to display content or collect input from users. Instead, they operate more as a complete view rather than as a reusable component meant to be invoked from multiple places within the application.

This differentiates the two in terms of their purpose and structure: blocks serve as modular components that can enhance consistency and reduce redundancy within the design, while screens focus on delivering specific user experiences and interactions. Understanding this distinction helps in designing applications that are efficient, maintainable, and user-friendly.