For the last four years, Debian and Ubuntu have been in the top three Linux distributions on Distrowatch. Since 2005, neither has been out of the top six. Together, they form one of the greatest influences on Linux development, and that influence seems likely to continue for the foreseeable future. They remain closely related, although if you look closely subtle differences in direction and orientation start to emerge
You may have heard that Debian is a distribution for experts, and Ubuntu for beginners. That is true, so far as it goes. However, that distinction is more historic than contemporary.
After Ubuntu burst on to the scene in late 2004, it spent several years making the desktop easier to use, especially for non-English speakers. However, thanks to free licenses, Ubuntu's improvements have spread to most desktop environments.
Moreover, Ubuntu's days of interface innovations are largely in the past. Under the direction of the parent company Canonical, Ubuntu development has been focused elsewhere. For over six years, the emphasis was on the development of the Unity desktop into a common interface for phones, tablets, and desktops. Meanwhile, Canonical seems more concerned with OpenStack, embedded systems and servers. Although the recent abandonment of Unity in favor of GNOME could mean a return to innovation on the Ubuntu desktop, it is still too early to tell. For now, Ubuntu seems no more innovative than Debian.
At the same time, modern Debian is easier to install than ever before, and is imitating Ubuntu with Long Time Support releases for users who value stability over the latest software. Modern Debian is also focused on its role as the source of other distributions, including not only Ubuntu, but also distributions like Linux Mint, the distribution that has been consistently first on Distrowatch in the last four years.
Today, Debian can best be described as a distribution for everyone, easy to install for anyone who can follow instructions, but with the potential for detailed control that will satisfy experts.
Yet these general descriptions are only part of the story. Despite their common origin, Debian and Ubuntu differ in their installers, desktop environments, administration, and communities as well.
Debian vs. Ubuntu: Installation
Contrary to the lingering myth, modern Debian is no harder to install than any other distribution. In fact, with the Debian Installer available for ten hardware architectures and in text, graphical and voice formats, and with an expert mode for troubleshooting, if you cannot install Debian on your hardware, then very likely you will be unable to install any Linux distribution.
In comparison, Ubuntu's installer concentrates on 32 and 64 bit versions of Intel architecture for desktops and servers, although in recent years it has moved into ARM development as well. Nine alternatives or "flavors," are available, ranging from ones for specific purposes, such as the educational-oriented Edubuntu, and the Chinese language Kylin to ones with different default desktop environments, such as Lubuntu, which installs LXDE and Xubuntu, which installs Xfce.
By default, all these choices for Ubuntu use an installer designed to require a minimum of user input. However, in the event of difficulties, Ubuntu uses an a rebranded version of Debian's as an expert installer.
Debian vs. Ubuntu: Desktops
Between 2010-17, Ubuntu developed its own desktop called Unity. However, the 18:04 release will mark a return to GNOME as the default desktop. Other desktop environments continue to be available either from the repositories or from different flavors of Ubuntu, such as Xubuntu, Lubuntu, Ubuntu MATE and Ubuntu Budgie. Kubuntu, the KDE Ubuntu, is also available, although because of development politics, it is now developed independently, and no longer has a link on the Ubuntu web site. The same is also true of Unity, although the fork created after Ubuntu's return to GNOME has not existed long enough to release anything yet.
Debian, too, defaulted to GNOME for many years. The last two installers, though, offer half a dozen desktop environments, which saves time for those who like to have multiple desktops. The difference between Debian and Ubuntu lies mainly in when and how users install multiple desktops.
Debian vs. Ubuntu: Administration and Package Management
Debian installs by default with a root account and at least one non-privileged user. Ubuntu uses sudo, which hides the root password, and allows at least one user access to root privileges by entering their own password. You can set up sudo in Debian by leaving the root password blank during installation, but you can only remove sudo in Ubuntu after installation -- a more complicated task that should be researched before doing.
Using sudo has the advantage of minimizing the time that the root account is in use, but whether Ubuntu's sudo set up is more secure than Debian's classical arrangement is much debated. With both Debian and Ubuntu, users might consider setting up another sudo setup that is more in agreement with their concepts of security.
Debian's packages pass through the Unstable and Testing repositories, ending in Stable with the release of a new version. In between releases, Update and Backport help keep Stable current, and users can also choose between the self- explanatory Old Stable and Experimental. All these repositories are divided into three sections: main, which contains free- licensed packages, contrib, which contains free-licensed packages dependent on proprietary software, and non-free, which contains proprietary packages. Of these three, only main is included on the install DVDs; contrib and non-free must be added to the sources by editing the /etc/apt/sources.list file.
This arrangement makes Debian technically free -- if not recognized as such by the Free Software Foundation -- while providing users with other packages they might want and encouraging the non-standard packages to maintain a higher standard than they would probably have if, like Fedora, all non-free and contrib packages were maintained by third parties.
In comparison, Ubuntu repositories are organized by the organization responsible for them. Main contains software supported by Canonical, while software in Universe is supported by the Ubuntu community. Proprietary drivers are in Restricted, and software with legal complications is placed in Multiverse.
Both distributions use the .deb format, and many packages will run in either distribution. Usually, third party packages will also run in both so that only one package needs to be maintained, but, increasingly, some packages built by Ubuntu will not run in Debian. After thirteen years, the two distributions are beginning to grow apart, despite the disappearance of some differences with the announcement that Ubuntu is abandoning developing Mir as a replacement for the X Window System. Instead, like Ubuntu, it is moving towards using Wayland as a replacement.
In addition, starting in 2016, Ubuntu has also promoted Snap packages: universal packages that contain all necessary dependencies, and should eventually work on all Linux distributions. So far, there is no official plan to replace .deb packages with Snap ones except in embedded systems, but many speculate -- contrary to official statements from Ubuntu -- that such a change is only a matter of time.
Debian vs. Ubuntu: Governance and Community
Debian is a community distribution, in which all those who have passed the tests to become a Debian maintainer and selective non-maintainers elect the project leader and vote in referendum on major policy issues. Many decisions, especially on legal matters, are debated at length in Debian forums, especially debian-devel and debian-legal.
Ubuntu, though, is more complicated. On day to day matters, Ubuntu runs like a community distribution, with a Community Council and Technical Board, as well as various sub-committees. However, Mark Shuttleworth, Ubuntu's founder, has appointed himself Benevolent Dictator for Life, and has been known to over-rule community decisions in the interests of his company Canonical. Once or twice, this arrangement has led to near community revolts, and complaints about the lack of a clear definition of community.
Debian vs. Ubuntu: Bottom Line
Despite these differences, the interaction between Debian and Ubuntu remain close. Although some Debian members feel that Ubuntu does not give Debian enough credit, others have been known to work for both distributions. Members of both distributions also attend the annual Debconf conference.
Yet for users -- especially potential contributors -- the two distributions offer increasingly different choices. Debian, for instance, remains a general purpose distribution, as influential as the source of dozens of other distributions as for itself. In comparison, Ubuntu increasingly reflects the business interests of Canonical. Recent Ubuntu releases have offered little new for desktop users, but the same might be said of Debian, since it has reached a level of maturity where the gaps in software are increasingly few.
Perhaps Debian and Ubuntu can best be considered as two distributions in a symbiotic relationship, with each benefitting the other. Ubuntu continues to rely on Debian packages for the source of its own packages. Yet, in return, Ubuntu has aided Debian, partly by innovations such as apt, a simplified package installer, and even more so by increasing the popularity of Debian alongside its own. Without this symbotic relationship, the recent history of Linux would be more impoverished than anyone could imagine.