Comparing structure and content

The structure of requirements and specifications overlaps in some areas, but their focus remains different. Product requirements documents (PRDs) define why the product is built and what it should do. They include a product vision, goals, user personas, and user stories describing expected behavior from the user’s perspective. These parts ensure that the team understands the value and purpose before development begins.^[1]

Product specifications, on the other hand, expand on those foundations. They describe how the product will function and what standards it must meet. A specification can also include user stories and personas to give engineers context, but it adds layers such as system architecture, performance benchmarks, and compliance criteria. Together, both documents connect the user intent with technical execution, helping teams turn ideas into real, testable outcomes.^[2]