Since the Linux Mint developers are working with both bases, I think it's best to ask that question in this forum
My own impression is that besides using "apt" and ".deb" packages there is no more common ground between these two distros. Ubuntu may have started as a fork of Debian, but now it looks to me more like a sideline of Debian, a mostly independent distro which happens to use the same base package management, but the packages themselves are mostly incompatible (well, maybe Debian packages work better in Ubuntu than the other way around).
I think the main question now should be: How is Ubuntu being developed?
Does Canonical still take the original Debian code and modify it, or do they exclusively work with their own base and just happen to package their base stuff the same way Debian does?
In some way this reminds me of the situation with RPM-based distros: There's the Redhat family, (Open)Suse, various descendants of Mandrake ...
But except for their base packaging format they have barely anything in common. Well, OpenMandriva now also uses DNF and its GUI iteration Dnfdragora, but that still doesn't mean it's a fork of Redhat/ Fedora now.
So, what is your take on the question, be it as user or as developer/ maintainer?
Do you think it's still justified to call Ubuntu a fork of Debian, or has it become more of an almost independent sideline?
