please update and improve it if you can.
Fedora users or potential users sometimes have questions on how Fedora compares to other distributions in the Linux world. If you are wondering if Fedora is the right distribution for you, refer to the following pages:
http://fedoraproject.org/wiki/Overview
http://fedoraproject.org/wiki/Is_Fedora_For_Me
Linux distributions are very diverse and the following is not meant to a comprehensive comparison of all distributions nor are they a unbiased review or distribution bashing. Instead they are look at some other popular distributions from a Fedora perspective.
We, in the Fedora Project certainly believe in the diversity and encourage that by working close with upstream projects that benefits all Linux distributions and not just Fedora.
Debian
Debian is a community project and a popular Linux distribution.
Similarities
Like Fedora, Debian is very focused on free and open source software. A good judgement of whether a particular software project is truly free and open source software can be made on the basis of whether it is available via the Debian and Fedora repositories.
Both projects have a large body of collective knowledge from the community in the form of community governance, policies and packaging guidelines
Differences
Debian uses the deb format, dpkg package manager and apt-get dependency resolver. Fedora uses the rpm format and the RPM package manager and yum dependency resolver.
Debian has free, non-free and contrib repositories, while Fedora has a single global repository that contains only free software applications. Debian has a larger repository with over 20,000 software packages. Fedora has around 15,000 software packages taking into account that Fedora does not include a non-free or contrib repository.
Unlike Fedora, Debian does not follow a time based release model.
Ubuntu
Ubuntu is a popular Debian derivative and consequently many of the similarities and differences between Debian and Fedora apply to Ubuntu as well.
Similarities
Fedora and Ubuntu, both use many of the same command line tools, including cp, mv, rm, sudo, wget, etc.
Just as Fedora is sponsored by Red Hat, Ubuntu is sponsored by Canonical Ltd, a UK-based software company that profits mostly on charging for Ubuntu support. Ubuntu also has its own StackExchange website called Ask Ubuntu, which is similar to Fedora's Ask Fedora Askbot-based website. Ubuntu has a server and cloud like Fedora does.
Differences
Ubuntu is commercially supported by Canonical, while Fedora is a community project sponsored by Red Hat.
Ubuntu is a based on the Debian but Fedora is not a derivative and has a more direct relationship and stays close to many upstream projects.
Ubuntu has more lax policies involving proprietary or patent encumbered software and selectively tolerates it to some extent.
Ubuntu uses the deb format, dpkg package manager and apt-get dependency resolver. Fedora uses the rpm format and the RPM package manager and yum dependency resolver.
Fedora use many DEsktop Manager (gnome,kde,xfce,lxce called spin) Ubuntu has the same but their default manager is Unity
openSUSE
openSUSE was founded in part as a response to Fedora and hence has many similarities
Similarities
Like Fedora, openSUSE uses RPM as a package manager
openSUSE also has a time based release model although Fedora has a new release every six months and openSUSE has a new release every nine months instead
openSUSE has adopted the Fedora trademark license agreement with a few minor differences
openSUSE has in large part adopted the Fedora Packaging guidelines as well
Differences
openSUSE uses the zypper dependency resolver instead of yum although yum is available in the openSUSE repository.
openSUSE is freely available but also sold as a retail boxed product with limited commercial support from Novell while Fedora is a community project with no retail business.
Mandriva
Similarities
Like Fedora, Mandriva uses RPM as a package manager
Mandriva has adopted the Fedora licensing guidelines with few minor differences
Mandriva uses the Red Hat network configuration file layout
Many Mandriva packagers synchronize their packages with the style and patches found in the corresponding Fedora packages
Differences
Mandriva uses the urpmi dependency resolver instead of yum although yum is available in the Mandriva repository
Mandriva has an official non-free repository for redistributable but not Free software, and a somewhat more relaxed patent policy
Mandriva has a home-grown set of configuration tools, written in perl with GTK+ 2 bindings, organized in the Mandriva Control Center front end
Mandriva uses its own graphical network configuration tool and status applet, rather than NetworkManager
Mandriva has a for-sale commercial edition, the Powerpack, which includes some non-redistributable commercial software and some support
Mandriva requires all shared libraries to be split into separate packages, and provided in both x86-32 and x86-64 form (the x86-64 library packages have the prefix lib64)