The source and target database steps allow you to specify the SQL Server databases that will be compared. For more details on the database connection settings, see SQL Schema Compare Add Databases.
Even though we refer to the SQL Server database as the "source" or "target", the command line can switch them, so the source can become the target and vice versa. More details on setting the target database are included in the Log Files and Options step.
Below is the xml fragment that contains the SQL Server databases:
<LeftDatabase>
<SqlServer>DEVSRV002\SQL2016</SqlServer>
<DatabaseName>AdventureWorks</DatabaseName>
<TrustedConnection>true</TrustedConnection>
</LeftDatabase>
<RightDatabase>
<SqlServer>DEVSRV003\SQL2019</SqlServer>
<DatabaseName>AdventureWorks</DatabaseName>
<TrustedConnection>true</TrustedConnection>
</RightDatabase>