1. 1. Architecture and Language: Cypress is built on JavaScript and uses a different architecture than Selenide. Cypress operates directly in the browser and runs alongside the application being tested, allowing for real-time reloading and instant feedback. On the other hand, Selenide uses WebDriver and operates outside the browser, executing commands remotely. This difference in architecture affects how tests are written and executed.

2. 2. Test Execution Speed: Cypress has a reputation for being faster than Selenide due to its ability to directly communicate with the browser and the absence of network calls. Cypress can execute tests in real-time without any additional waiting or synchronization, resulting in faster test execution. In contrast, Selenide relies on WebDriver and requires explicit wait times, leading to potentially slower test runs.

3. 3. DOM Control and Manipulation: Cypress offers a unique feature called Automatic Waiting. It intelligently waits for elements to appear and become interactable before performing actions, without the need for explicit waits or synchronization. This simplifies test code and ensures that tests are more stable. In comparison, Selenide requires explicit waits and synchronization commands to handle asynchronous operations, making the test code more complex.

4. 4. Debugging Capabilities: Cypress provides an extensive set of debugging tools that make it easier to diagnose and troubleshoot issues. It offers real-time reloads, automatic screenshots on failure, video recording, and interactive error messages. Selenide, while supporting screenshots and error messages, may require additional configuration or external libraries for similar debugging capabilities.

5. 5. Cross-browser Testing: Cypress primarily focuses on testing within a single browser, Chrome. It optimizes the testing experience by tightly integrating with Chrome's internals. In contrast, Selenide supports cross-browser testing and can run tests on different browsers by leveraging WebDriver's capabilities. This makes Selenide a better choice for projects requiring extensive cross-browser compatibility testing.

6. 6. Community and Ecosystem: Cypress has gained rapid popularity in recent years and has a growing community. It offers a rich ecosystem of plugins, custom commands, and a centralized dashboard for managing tests. Selenide also has a strong community but may have a slightly smaller ecosystem compared to Cypress. The availability of community support and resources can influence the ease of adoption and development experience.

In Summary, Cypress and Selenide differ in architecture and language, test execution speed, DOM control and manipulation, debugging capabilities, cross-browser testing support, and community ecosystem.