Hi! Co-maintainer here, you can find the differences in the github repo: https://github.com/ublue-os/bluefin
I checked the github page you link and can find no differences listed, just three bullet points that appear to have be written by a PR team. You say an Ubuntu Desktop experience melded with Fedora Silverblue. Don't you mean GNOME? Ubuntu isn't a desktop environment, it's a Linux distro. GNOME is the desktop environment. That seems like an embarassing blunder in your copy when you claim to be building a distro for "serious" developers.
If it weren't open source, I'd think this was a scam. Weird choice.
GNOME on Fedora 39 with the Pop Shell extension installed. For me, perfection :)