A builder is an image that bundles all the bits and information on how to build your apps, such as buildpacks, an implementation of the lifecycle, and a build-time environment that platforms may use when executing the lifecycle.
A buildpack is a unit of work that inspects your app source code and formulates a plan to build and run your application.
The lifecycle orchestrates buildpack execution, then assembles the resulting artifacts into a final app image.
A platform uses a lifecycle, buildpacks (packaged in a builder), and application source code to produce an OCI image.
A stack provides the buildpack lifecycle with build-time and run-time environments in the form of images.