1. Deployment Environment: Docker is primarily used for containerization, allowing developers to package applications and dependencies into a container that can run on any system with Docker installed. On the other hand, Sauce Labs is a cloud-based platform focused on providing automated testing tools for web and mobile applications.
2. Testing Capabilities: While Docker focuses on packaging and deploying applications, Sauce Labs specializes in providing a wide range of testing capabilities such as automated cross-browser and mobile testing, parallel testing, and real-time debugging tools.
3. Integration with CI/CD: Docker is commonly integrated into the CI/CD pipelines to automate the building and deployment of applications. In contrast, Sauce Labs is integrated into the testing phase of the CI/CD pipeline to ensure that applications are thoroughly tested across various platforms and environments.
4. Scalability: Docker containers can be easily scaled horizontally or vertically to meet the demands of applications or services. On the other hand, Sauce Labs provides scalable testing infrastructure to run tests concurrently on multiple virtual machines and devices, ensuring quick feedback on application performance and functionality.
5. Security Features: Docker provides various security features such as isolation of containers, resource limitations, and secure image repositories. Sauce Labs, being a cloud-based platform, offers security measures like data encryption, secure tunnels for testing on internal servers, and compliance with industry standards to protect sensitive data during the testing process.
6. Management Complexity: Docker requires the management of container orchestration tools like Kubernetes for deployment, scaling, and management of containerized applications. In contrast, Sauce Labs handles the infrastructure management, allowing users to focus solely on writing and executing tests without the need for complex setup or maintenance tasks.

In Summary, Docker and Sauce Labs differ in their primary focus on containerization and deployment versus cloud-based automated testing tools, respectively, with differences in testing capabilities, integration with CI/CD, scalability, security features, and management complexity.