SQL

I've got a web site that I need to start hosting that is using MySQL. I'm
kinda new to this SQL database stuff. I know that a RH6.1 install I have
has a postgreSQL server (installed but not running). Do these two different
SQL Servers use the same database structure? Is MySQL better than
postgreSQL? If anyone has any books or links that I could get more
information from I would appreciate it.

Don