An image is a packaged filesystem and startup configuration. A container is a process created from that image. Pulling an image prepares the local image store; it doesn't start the application. Use a tag to identify the release you need, then inspect the available references before you run anything. Tags can change in a remote registry, so a production release may use an immutable digest instead. In this local workspace, image pulls use a fictional registry model and make no network request. Your tasks distinguish the required version from a similar image that happens to be available.