A container image, much like a VM image (though much smaller), is the "blueprint" containers are created from. All dependencies, as well as your application code, is baked into an image. Multiple containers can be created that use the same image.
Stacks offer a powerful way to declaratively manage multiple containers, and their deployments to the Cycle platform. Using stacks, you are able to configure every aspect of your applications ahead of time, save it to your version controlled repo, and have Cycle automate the deployment any time you make a push.
A stack build is a deployable snapshot of a stack. It contains all built images and their configurations, and can be directly deployed to an environment. The philosophy is the same as with an individual container image -- they are atomic, and hold everything they need to be deployed.
When you first import a stack, it will also create an initial build. Every build generates a "build log", containing all the output generated when Cycle built the images.
If you've got questions about the platform or need some help getting started, our team is more than happy to assist. Whether you're new to containers or just new to Cycle, reach out to us via livechat by clicking the blue circle in the bottom right corner. Join our Slack channel, and get help from the dev team or other members of the community.