The identifier for the content (image layers + manifest) is the hash of the content, and the has serves as an "address", the registry repo + tag is basically a pointer to a hash.
Thank you. Would other type of addressing be something like offset-based or address-based? Just trying to imagine different ways a file can be packed as I never gave it much thought.
I'm pretty sure it's just the difference between a file being named foo.tar.gz and (SHA-256 of the file).tar.gz[0] - the content and storage are the same, it's just that the canonical name is a hash of the contents rather than being arbitrary.