What is the exact difference between SizeRootFs and SizeRw in Docker containers?
SizeRootFs is the total size of all the files in the container, in bytes. If you were to export the filesystem of the container as a tarball, it would be about that size.
SizeRw is the size of the files which have been created or changed, if you compare the container to its base image. Just after creation, this should be zero; as you modify (or create) files, this will increase.