The source and target database steps allow you to specify the SQL Server databases that you want to compare. For more detail about the database connection settings, see SQL Data 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>DEVSRV003\SQL2019</SqlServer>
<DatabaseName>AdventureWorks</DatabaseName>
<TrustedConnection>true</TrustedConnection>
</LeftDatabase>
<RightDatabase>
<SqlServer>DEVSRV002\SQL2016</SqlServer>
<DatabaseName>AdventureWorks</DatabaseName>
<TrustedConnection>true</TrustedConnection>
</RightDatabase>