Earlier quoted context omitted.
I think it's fair to consider them as different distros, at least in practice, given how much the choice of a desktop environment can affect the user experience. A lot of the software available by default will differ, obviously. Instructions about how to use the system differ, as well. The default capabilities and functionality will differ. The bugs affecting them will differ. All of those differences add up.
"Different defaults" is not really something that differenciates distros. Lubuntu, Xubuntu, Kubuntu etc have a name: They're remixes of an existing distro.
It is the defaults that matter. They're what give a particular distribution its unique characteristics.
Sure, you can go out of your way to install the software necessary to make one distribution comparable to some other distribution, but that doesn't mean they're really the same to begin with, even if their names may be similar.