1. Key difference 1: Language and syntax: Cucumber uses a domain-specific language called Gherkin, which is a plain-text format that uses keywords like Given, When, and Then to define test scenarios in a business-readable manner. On the other hand, TestCafe uses JavaScript as its primary language, allowing testers to write tests using familiar programming concepts and syntax.

2. Key difference 2: Test execution: Cucumber relies on step definitions written in a programming language (such as Java or JavaScript) to execute test scenarios. These step definitions link the Gherkin syntax to actual test code. In contrast, TestCafe directly executes test code written in JavaScript using its own test runner.

3. Key difference 3: Cross-browser testing support: TestCafe provides built-in cross-browser testing support, allowing testers to run tests on multiple browsers without any additional setup. Cucumber, on the other hand, requires additional tools or frameworks (such as Selenium) for cross-browser testing.

4. Key difference 4: Test isolation and parallel execution: TestCafe runs tests in separate instances of a browser, providing test isolation and avoiding interference between tests. It also supports parallel test execution out of the box, allowing tests to run concurrently. In contrast, Cucumber requires additional setup and configuration to achieve similar levels of test isolation and parallel execution.

5. Key difference 5: Reporting and test result visualization: TestCafe offers built-in reporting capabilities, providing detailed test result reports and visualizations. It generates HTML reports that can be easily shared with stakeholders. Cucumber implements reporting through the use of plugins or additional libraries, which need to be configured separately to generate reports and visualize test results.

6. Key difference 6: Integration with development frameworks: TestCafe integrates well with popular JavaScript frameworks (like React, Angular, and Vue.js), allowing testers to write tests using the same libraries and components used in the application under test. Cucumber, although also compatible with JavaScript, requires additional configuration and adaptation to seamlessly integrate with specific frameworks.

In summary, Cucumber and TestCafe differ in their language and syntax, test execution approach, cross-browser testing support, test isolation and parallel execution capabilities, reporting and test result visualization, as well as integration with development frameworks.