1. Mocking and serving data: JSON Server allows you to quickly mock and serve data using a simple JSON file. It automatically creates RESTful routes for the data and supports various CRUD operations. On the other hand, Postman does not provide native mocking capabilities, as it primarily focuses on testing and documenting APIs.

2. GUI interface vs Command line interface: Postman provides a user-friendly graphical interface that allows developers to easily send HTTP requests, test APIs, and view responses. It also provides features like authentication, environment variables, and response validations. On the contrary, JSON Server is a command-line tool that requires minimal configuration and can be easily integrated into development workflows.

3. Real-time collaboration and sharing: Postman offers cloud-based features that enable real-time collaboration among team members. It allows users to share collections, collaborate on API development, and synchronize changes across multiple devices. JSON Server, being a simple command-line tool, does not offer built-in collaboration features.

4. Middleware and request/response manipulation: Postman provides a wide range of functionalities through its pre-request scripts and response scripts. These scripts allow developers to add custom logic, manipulate requests and responses, and perform complex API testing scenarios. JSON Server, being a lightweight server, does not provide the same level of built-in middleware and request/response manipulation capabilities.

5. Documentation and API testing: Postman excels in providing comprehensive documentation features that help developers create detailed and interactive API documentation. It allows the creation of well-structured documentation with rich formatting, examples, and response code snippets. JSON Server, being mainly focused on data mocking and serving, does not provide native documentation generation capabilities.

6. Testing automation and integration with CI/CD: Postman offers advanced capabilities for automating and integrating API testing with continuous integration and continuous deployment pipelines. It provides a developer-friendly interface, command-line runner, and Postman API for seamless integration into various development workflows. JSON Server, being a stand-alone tool, does not offer the same level of testing automation and CI/CD integration features.

In summary, JSON Server is a lightweight tool for quickly mocking and serving data during prototyping and testing, while Postman is a comprehensive API testing and documentation platform with rich features like real-time collaboration, request/response manipulation, and automation capabilities.