1. User Interface: Hoppscotch provides a clean and intuitive interface for making HTTP requests with various customization options, while OpenAPI is primarily a specification format that describes RESTful APIs.
2. Ease of Use: Hoppscotch is more user-friendly and beginner-friendly compared to OpenAPI, as it offers a visual way to interact with APIs without needing to understand the underlying specification details.
3. Collaboration Features: OpenAPI focuses on defining API specifications and supporting tools for developers, while Hoppscotch prioritizes collaboration features such as sharing requests and workspaces with team members for enhanced productivity.
4. Authentication Options: Hoppscotch supports a wide range of authentication methods, making it easier to test APIs that require authentication compared to OpenAPI, which does not have built-in authentication mechanisms.
5. Real-time Response: Hoppscotch provides real-time response updates as the API request is being made, allowing users to monitor progress and troubleshoot issues more effectively than OpenAPI, which focuses on defining API structure rather than real-time interaction.
6. Open Source Community: Hoppscotch has a vibrant open-source community that actively contributes to its development and adds new features, making it more dynamic and responsive compared to OpenAPI, which is maintained by the OpenAPI Initiative.

In Summary, Hoppscotch and OpenAPI have key differences in their user interface, ease of use, collaboration features, authentication options, real-time response capabilities, and community engagement.