Mysql

What is MySQL?
MySQL, the most popular Open Source SQL database management system, is developed, distributed, and supported by Oracle Corporation.

What is MariaDB?
MariaDB Server is one of the most popular open source relational databases. It's made by the original developers of MySQL and guaranteed to stay open source. It is part of most cloud offerings and the default in most Linux distributions.

MariaDB vs MySQL:
MariaDB is a fork of MySQL, the database structure and indexes of MariaDB are the same as MySQL.
- data and table definition files are compatible
- client protocols, structures, and APIs are identical
- MySQL connectors will work with MariaDB without modification

Links:
Compatibility & Differences
MariaDB versus MySQL: Compatibility
Function Differences between MariaDB and MySQL
MySQL vs MariaDB: Performance
MySQL
MariaDB