You could kind of say that all Linux distros are releases of the upstream Linux kernel - I know its stretching the analogy with Elm a bit, but …
Each Linux distro has its own name, logo and identity. They all feed from a huge number of upstream projects and try to bring them together into a stable curated system. They all create opportunities to feedback patches to those upstream projects. Some have their own private repos and kernel patches (but must make those available as per the GPL) - RedHat Enterprise Linux being the obvious example.
Would put a different name and logo on it, but be completely open about the fact that it is actually Elm with a few modifications.