Replicator enables you to easily mirror contents of your database to a database in different (or same) format - it's a heterogeneous table data replicator. Any changes that occur in source database will get picked up on next synchronization and a minimal set of required updates will be applied to target database to bring it in sync with the source.
For replication to be set, equivalent tables need to already to exist in both (source and target) databases.
Advanced users can customize the comparison and synchronization process in many ways - but we worked hard to make the straightforward database replication as easy as possible.
To start, take a look at the getting started guide. Unless your source database is constantly changed, synchronization should bring both database is exact same state and further comparison will find no differences between the two.
Replication is usually set up to run repeatedly - many customers have it running hourly or even every few minutes. Optimal period depends on time needed to do the replication - you shouldn't run replication again on if there is one already running for same databases. Also, if you plan to run several replications at once, make sure to specify different temporary file folder for each replication, so that temporary files don't step over each other.