MariaDB is a community-developed fork of the MySQL relational database management system, the impetus being the community maintenance of its free status under the GNU GPL. As a fork of a leading open source software system, it is notable for being led by its original developers and triggered by concerns over direction by an acquiring commercial company Oracle. Contributors are required to share their copyright with Monty Program AB.
MariaDB is a fork of the MySQL database project that provides a drop-in replacement for MySQL. It preserves API/ABI compatibility with MySQL and adds some new features.
The original company behind MySQL, MySQL AB, were bought out by Sun which was then bought by Oracle. Recent changes made by Oracle indicate they are moving the MySQL project to be more closed. They are no longer publishing any useful information about security issues (CVEs), and they are not providing complete regression tests any more, and a very large fraction of the mysql bug database is now not public.
MariaDB, which was founded by some of the original MySQL developers, has a more open-source attitude and an active community. We have found them to be much easier to work with, especially in regards to security matters.
Note : Now Fedora-19 is coming with default DB As MariaDB instead of MySQL DB.
[from Fedora 19 Release ]: We would like to replace MySQL with MariaDB in early development cycle for Fedora 19. Original MySQL implementation packaged as mysql will be renamed to community-mysql and package mysql will retire as of Fedora 19. It means the name "mysql" will become only a virtual provider for compatibility reasons. MariaDB will become the default and will include Provides/Obsoletes for mysql, while community-mysql will only include Provides for functional packages (not -devel packages) in order to avoid ambiguity when choosing one from two packages providing the same symbol. The community-mysql packages will be installed after users explicitly request so. Also, we do not intend to support concurrent installation of both packages on the same machine; pick one or the other. The only packages, that will be able to be installed in parallel will be client libraries (mariadb-libs and community-mysql-libs).
Benefit to Fedora
Fedora will have a truly open-source MySQL implementation and won't depend on what Oracle decides to do with MySQL in the future. Compared to MySQL, MariaDB is faster in some cases, it includes some new engines and features, while the existing engines and features are enhanced and still compatible.
More Interesting One from ZDNet :
Wikipedia moving from MySQL to MariaDB http://www.zdnet.com/wikipedia-moving-from-mysql-to-mariadb-7000008912/