PostgreSQL excels at complex, write-heavy workloads with advanced SQL features, rich data types like JSONB, and strict ACID compliance, making it ideal for financial systems and analytics. MySQL prioritizes speed and simplicity for read-heavy applications, offering lightweight architecture perfect for web apps, CMSs, and MVPs. PostgreSQL provides superior extensibility, query optimization, and enterprise features, while MySQL delivers faster performance for simple queries and lower resource consumption. The choice depends on workload complexity, data consistency requirements, and scalability needs.