Compare two similar Postgres databases for differences

Have a look at the Stack Overflow Q & A, How to check difference between two databases in PostgreSQL?; in particular Another PostgreSQL Diff Tool (apgdiff) (schema comparison only). Apgdiff is recommended by Alexander Kuznetsov - a published database book author and bit of a guru.

Maybe also look at Liquibase or Compare Database Table Data.

There are also commercial products - e.g. Altova Database Differencing with DiffDog

For schema comparisons, pgadmin4 has a Schema Diff feature (in beta as of 26 Jun 2020). https://www.pgadmin.org/

There is also:

• PgDiff
• and the tool I'm working on Postgres Compare which is free while in beta