Which tool should I buy to synchronize databases?
Replicator will compare all tables one by one, noting the differences in data. It will then apply absolutely minimal set of changes to the target database to make its data same as data in source database. Usually, this will amount to a few dozens or hundreds of UPDATE statements, and bulk insert of new data, which is very fast. Advantage of this approach is that your target database is usable all the time. Its state is never half-empty, as we don't load all data on each run. So, replication can be scheduler often. Many customers do the replication every 15 minutes or so.
However, as Replicator doesn't create your target database, you may need Full Convert to completely recreate your target database at least once - if you don't already have compatible tables in the target database. If you only need to replicate data overnight, when nobody is using the target database, you may choose to scheduler a Full Convert migration. It will fully overwrite affected target tables, dropping them and recreating them as it goes (by default).