Docker containers are lightweight virtualization technology that shares the host operating system kernel, while virtual machines (VMs) require a complete operating system. Docker containers start quickly (in seconds), consume fewer resources, and have small image sizes; virtual machines start slowly (in minutes), require more resources, and have large image sizes. Docker containers provide process-level isolation, while virtual machines provide hardware-level isolation. Docker is better suited for microservices architecture and continuous integration/continuous deployment (CI/CD) scenarios.