KS DB Merge Tools
for MS Access
aka AccdbMerge
for SQL Server
aka MssqlMerge
for MySQL
and MariaDB
for SQLite
for PostgreSQL

Compare ad hoc query result

Open databases (see Schema changes summary use case) and 1click 'Query result diff' toolbar button:

In the opened Query result diff tab specify 2mapping type, 3query text and 4click Run.

Then 5specify expected unique key fields and 6click OK:

and get the result:

where you can 7apply additional filter to show only new and/or changed records: