How to compare MySQL database schemas

Navicat is able to do that for you. It will also synchronize schema and/or data between two mysql database instances. I've used it with success in the past.

http://www.navicat.com/en/products/navicat_mysql/mysql_overview.html

There is a screenshot of the data and structure synchronization tool here:

http://www.navicat.com/en/products/navicat_mysql/mysql_detail_mac.html#7

Perhaps a bit late to the party, but I've just written a simple tool in PHP to compare MySQL database schemas:

PHP script to compare MySQL database schemas How to use the script

It exports the schema and serialises it before doing the comparison. This is so that databases can be compared that reside on different hosts (where both hosts may not be accessible by the PHP script).

Edit:

Python Script

I use SQLyog:

http://www.webyog.com/en/

It isn't free but is a very good tool and has saved the cost of it's license many many times over. I'm in no way affiliated with the company, just someone who has used a number of MySQL tools.

Free trial(30-day) available from here.