Service-Oriented Architecture (SOA) and Microservices are two popular architectural styles in modern software development. While both approaches aim to enhance the flexibility and scalability of systems, they differ in their design principles and implementation strategies. Understanding the distinctions between SOA and Microservices is crucial for architects, developers, and decision-makers looking to optimize their systems for efficiency and performance. This article explores the fundamental differences between SOA and Microservices, delving into key characteristics, architectural principles, scalability considerations, communication strategies, deployment practices, performance metrics, testing methodologies, and real-world case studies to provide a comprehensive overview of these two paradigms.