MySQL

PostGreSQL

Free and Open Source Database released under the GPL License.

Free and Open Source Database released under the BSD License.

Supports multiple table types such as InnoDB, MyISAM etc.

Has it's own built in table type.

InnoDB table type supports foreign keys and referential integrity.

It Supports foreign keys and referential integrity.

Nested queries are still not supported in most versions.

Nested queries are supported.

If you distribute mySQL with a product with which you are making money, then you need to obtain a commercial license for it.

No commercial license is required for PostGreSQL.

No support for transaction processing.

Support for transaction processing.

No support for stored procedures yet.

Support for stored procedures.

MySQL is fully threaded so it can operate on different tables simultaneously.

PostGreSQL is not fully threaded so it cannot perform parallel operations.

Has no support for cursors and rollbacks.

Supports cursors and rollbacks.

Good Documentation.

Documentation is not very comprehensive.

Follows some of the ANSI SQL standards.

Strict follower of the ANSI SQL Standards.

Does not support Views.

Supports Views.

Does not support Unions and Full Joins

Supports Unions and Full Joins

Database design is generally simpler.

Database design is simple but not as simple as mySQL.

Relatively faster.

Relatively slower though the speed differential is getting insignificant.

Suitable for Web based simple deployments.

Suitable for more complex deployments.

Not a True RDBMS.

True RDBMS.