Waterfall and Agile represent two very different ways to structure work. Waterfall follows a step-by-step path where each phase must finish before the next begins. The entire project is planned at the start, with separate phases following in order: requirements, design, implementation, testing, deployment, and maintenance. In contrast, Agile uses a repeating, step-by-step approach. Planning evolves throughout the project rather than being completed at the beginning. Phases overlap and repeat in short cycles called iterations or sprints. While Waterfall gathers feedback mainly after final delivery, Agile includes continuous feedback throughout development. This structural difference greatly affects how teams work.

Waterfall creates clear but rigid boundaries between phases and often between team specialties. Agile blurs these boundaries, encouraging cross-functional teamwork and adaptation based on new information. The choice between these structures isn't just about scheduling. It reflects fundamentally different ideas about how complex work should be organized and how teams should collaborate.