I know Mandrake Linux, and I used it for some time as my main distribution. Like Ubuntu they were striving for a user-friendly distribution, but they never got the the level of consistency Ubuntu had.
Why? Because they chose KDE at the beginning, but they didn't stick with their choice and did what every other distribution did: let users choose between KDE and Gnome. And spent time to have all their tools look "kinda OK" in both desktops with cross Qt-Gtk themes, and Gnome users got a not so great experience but they kept shouting that Gnome users were just as important to them as KDE users, etc.
So in short they thought of themselves a "Linux distribution", a way to install Linux and related software. On the other hand, Ubuntu considers itself an OS, and upstream software is just a way for them to achieve the degree of quality they want.
You see that also when Ubuntu releases Unity: they want their OS to work this way, while Mandrake always focused on (1) the installer and (2) the control panel where you configure stuff, thinking "the desktop is Gnome/KDE's job, let's just ship what they make".
There was other reasons why Ubuntu worked better than Mandrake: one is that they used the superior dpkg while Mandrake was using RPM. (RPM got better recently, but back in the day it was a huge pain). Honestly I felt for many years that a user-friendly distribution based on dpkg would bring the best of both worlds, and that's what Ubuntu was.
Also Ubuntu arrived as the right time, when it was possible to have a fully plug-and-play distribution if your hardware is standard enough. I don't think they could have achieve that in the 90's.
And of course marketing. Ubuntu have been very good at marketing, and that's a good thing.
Why? Because they chose KDE at the beginning, but they didn't stick with their choice and did what every other distribution did: let users choose between KDE and Gnome. And spent time to have all their tools look "kinda OK" in both desktops with cross Qt-Gtk themes, and Gnome users got a not so great experience but they kept shouting that Gnome users were just as important to them as KDE users, etc.
So in short they thought of themselves a "Linux distribution", a way to install Linux and related software. On the other hand, Ubuntu considers itself an OS, and upstream software is just a way for them to achieve the degree of quality they want.
You see that also when Ubuntu releases Unity: they want their OS to work this way, while Mandrake always focused on (1) the installer and (2) the control panel where you configure stuff, thinking "the desktop is Gnome/KDE's job, let's just ship what they make".
There was other reasons why Ubuntu worked better than Mandrake: one is that they used the superior dpkg while Mandrake was using RPM. (RPM got better recently, but back in the day it was a huge pain). Honestly I felt for many years that a user-friendly distribution based on dpkg would bring the best of both worlds, and that's what Ubuntu was.
Also Ubuntu arrived as the right time, when it was possible to have a fully plug-and-play distribution if your hardware is standard enough. I don't think they could have achieve that in the 90's.
And of course marketing. Ubuntu have been very good at marketing, and that's a good thing.