This is a great comparison, written I believe by one of the Nix devs.
As far as Gobo is concerned, the outdated parts is that the /System/Links/{Executables,Libraries,...} has been replaced by /System/Index/{bin,lib,...} which makes it easier to build packages (less compatibility issues to deal with, since /usr is a symlink to /System/Index). So it's easier for a user to compile their own stuff and get it working.
And of course, the comment at the end about the project inactivity no longer applies: Gobo is alive and well. :)
As far as Gobo is concerned, the outdated parts is that the /System/Links/{Executables,Libraries,...} has been replaced by /System/Index/{bin,lib,...} which makes it easier to build packages (less compatibility issues to deal with, since /usr is a symlink to /System/Index). So it's easier for a user to compile their own stuff and get it working.
And of course, the comment at the end about the project inactivity no longer applies: Gobo is alive and well. :)