To start a comparison between two databases click on the "Compare Databases" button on the "Home" tab of the ribbon. The "SQL Server Database Selection" dialog window that appears allows you to choose the server(s) where the databases you wish to compare reside as well as the databases themselves.
From this window you can also access the Comparison Options that will be applied during the comparison.
Total compare from data to schema with SQL Comparison Toolset. Learn more > >