The folks behind Debian LTS and Freexian ELTS are all Debian members/contributors, and the Debian LTS changes end up in the Debian archive, while the Freexian ELTS ones are publicly available, just in an external archive.
https://wiki.debian.org/LTS
https://wiki.debian.org/LTS/Team
https://wiki.debian.org/LTS/Funding
https://wiki.debian.org/LTS/Extended