MySQL and MariaDB are very similar and most software can use either of them without any problems or special configuration. There are some minor differences in performance, stability and technical features, but they are pretty minor.
We used to run Percona Server quite recently, which is almost identical to MySQL, but recently switched to MariaDB.
Looking at what you wrote in your other topic, Moodle supports MySQL and MariaDB, but needs a configuration flag to be set to work with MariaDB. That should be an easy fix though.