The top 3 differentiating points between Oracle and PostgreSQL databases are:

1. Licensing and Cost

Oracle: A proprietary, commercial database with significant licensing costs. It is often used in enterprise environments requiring advanced features like RAC (Real Application Clusters), Data Guard, and robust security.

PostgreSQL: Open-source and free to use. It's widely adopted for cost-effective projects, startups, and companies seeking flexibility without vendor lock-in.

1. Transaction Management and Concurrency Control

Oracle: Utilizes Redo Logs for recovery and Undo Logs for rollback, with advanced transaction isolation levels and locking mechanisms. It provides fine-grained control over large-scale transactional systems.

PostgreSQL: Implements Multi-Version Concurrency Control (MVCC), which minimizes locking by allowing multiple versions of a row to exist. It ensures high concurrency and performance for read-heavy workloads.

1. Advanced Features and Ecosystem

Oracle: Offers a mature ecosystem with advanced features like Partitioning, Materialized Views, Flashback Technology, and Advanced Security (TDE, VPD). It is ideal for high-volume OLTP and large-scale enterprise applications.

PostgreSQL: Provides powerful extensions (e.g., PostGIS for geospatial data, TimescaleDB for time-series data) and supports modern data types (JSON, arrays, etc.), making it ideal for flexible and extensible database architectures.

These points summarize the primary distinctions in cost, transaction management, and features, tailored to different use cases and environments.