The many available Linux distributions differ for a range of reasons including technical, organizational, and philosophical.
Technical variations include support for different hardware devices and systems or software package configurations. Organizational differences may be motivated by technical decisions but also by philosophical or even historical reasons. Some distributions specialise in use on desktops, servers or routers. Other criteria include security, including how quickly security upgrades are available; ease of package management; and number of binary packages available.
These tables compare the latest stable release of major distributions on a range of objective criteria. It does not cover the subjective merits of each operating system, branches marked as unstable/beta, nor compare Linux distributions with other operating systems.
Look at: http://en.wikipedia.org/wiki/Comparison_of_Linux_distributions