MariaDB is in most aspects identical to MySQL.

Differences between MySQL and MariaDB can be found at:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/
https://mariadb.com/kb/en/mariadb-vs-mysql-compatibility/

The MariaDB manual can be found at:
https://mariadb.com/kb/

The MySQL Reference Manual is available in various formats on
http://dev.mysql.com/doc.