Logical phase – The logical phase views the design objectives and challenges from the perspective of the project team. The primary goal of the logical phase is to map the conceptual design into logical components. The team uses the user scenarios (or use cases) identified in the conceptual phase to build a logical model of the components in an object-oriented software solution. Object-oriented solutions encapsulate business functionality in software representations of real-world objects, which are defined by classes in an object-oriented design.

Physical phase – The physical phase views the design objectives and challenges from the perspective of the developer. The primary goal of the physical phase is to apply the logical design to physical requirements and constraints. Because the physical phase approaches the design problem from the perspective of the developer and the task is to define the physical implementation, the technical specification document is the product of the physical design phase.