The PostgreSQL mental model that finally clicked for me

What i was learning Today i started learning PostgreSQL , the objective was to create a mental model to build a strong foundation and potentially a smooth learning curve for PostgreSQL . What confused me Coming from SQLite, confusion was inevitable.The initial assumption was that PostgreSQL would be smooth, that perhaps all i needed to do was change the app configuration from SQLite to PostgreSQL and everything else would remain untouched. To my surprise, the reality was a complete contradiction