What is the difference between Agile vs. Waterfall?

Although Agile is often viewed as the superior choice of methodologies, it does bring with it a handful of disadvantages to be aware of before fully committing. These include the following:

If customers do not have the time or the interest to work closely with the development team, the project will not have the feedback or insights it needs to progress.

If team members are not fully committed to completing the project effectively and efficiently, the self-management aspect of Agile falls apart.

Some tasks, or even certain subtasks, may be too time-intensive to be completed during a single sprint. To address these issues, teams either have to change priorities or introduce costly additional sprints.

Agile’s iterative and incremental nature is not as compatible with project governance or oversight. Teams that are incapable of self-governing are less likely to be able to be managed effectively.

The fact that Agile prioritizes working software over documentation sometimes means that essential notation gets left behind. This can be a problem, as comprehensive documentation helps make implementations more shareable, identifies the thinking behind specific decisions, and allows teams to more easily return to earlier stages.

Often, entrenched corporate processes, toolsets, policies, organizational structures, and controls are not conducive to agile. As such, effective Agile implementation demands wide-spread cultural change throughout the organization. This can lead to push back from individuals or departments that are accustomed to more traditional practices.

First described in 1970, the Waterfall methodology has seen consistent use among development teams for approximately half a century. This is because it delivers certain benefits, including the following:

The Waterfall methodology is perhaps the easiest to manage, with each stage attached to specific deliverables and a clear review process.

In projects where multiple components need to be designed to allow for integration with external systems, Waterfall’s approach (in which design is completed early in the process) is a clear advantage.

Product requirements are documented and agreed upon prior to the start of development, establishing a predictable and concrete set of features.

Increased planning and front-loaded documentation create a clear overview of potential costs. This allows for accurate budgeting.

Because the full scope of work is known in advance, measuring progress becomes simple and accurate. Progress is typically measured in the 'status report,' where work items are defined as green, yellow, or red when it comes to schedule, budget, and resources.

Goals are identified and established before development work begins, rather than remaining fluid to account for changing needs.

Team members have the bandwidth to work on other projects, only needing to commit their time during their designated stages.

Waterfall methodologies create an easier, more hands-off experience for customers; involvement by end users is not required except during the requirements and review stages.

With a clearer focus on planning and documentation, projects follow an established path, are easier to review, and results are more-clearly identifiable.

The rise in Agile attests to certain drawbacks in the traditional Waterfall methodology. These disadvantages include the following:

Because Waterfall relies on detailed early-stage planning, projects that encounter unexpected problems, roadblocks, or changing needs may be unable to adapt. Likewise, Waterfalls flow in only one direction; it may be impossible or very difficult to return to earlier stages to make changes.

Rigidly defined requirements leave very little room for inspiration, innovation, or creativity, and may prevent developers from taking advantage of unexpected opportunities during development.

Being less involved in development processes, customers may feel left out of the loop. Perhaps even more problematic is that customers may not be aware of what will be delivered until the project reaches completion. On the other side of the coin, developers themselves might not know what the expected outcome is for the customer, further widening the gap. Additionally, because testing occurs only at the end of the project, bugs and UX issues are more likely to sneak through.

Unclear deadlines for specific stages can lead to projects going over schedule. To make up for this, teams will sometimes rush through the last stages, including testing. This can lead to inferior products.

Requirements must be clearly identified and approved before any work can begin. If they are not, individual team members may interpret requirements differently, leading to a disconnect.

With so much effort expended in planning and documentation, fewer resources are available for the actual building of products.

Stricter project requirements are better suited toward Waterfall, while fewer requirements and regulations allow the creativity and freedom of Agile to shine.

Strict processes make Agile deployment very difficult and benefit more from a traditional Waterfall approach. Agile is more effective when processes are more flexible.

Waterfall is effective when customers, end users, and product owners are not interested in working closely with the development team. Those users who want increased involvement to benefit more from Agile.

Enhancing existing legacy projects, where features are already well defined and integrations are established, benefits from the Waterfall approach. If the project is breaking new ground and attempting something that hasn't been done, then Agile’s iterative approach enables teams to learn and adapt as they go.

The Waterfall methodology establishes a predictable outcome and works well with clearly defined deadlines and long-duration projects. Shorter deadlines that are more flexible work better within Agile.

Waterfall’s predictability is also well suited to inflexible budgets, where each action and expense needs to be documented early in the process. Agile demands less rigidity in budgeting, focusing on features and development speed, and not taking as strict of a stand on costs.

Smaller, well-defined projects are often better suited to Waterfall. Larger, more-complex projects benefit from the Agile approach.

When coordinating with remote workers or partnering with other organizations, Waterfall’s reduced need for in-person collaboration makes it a better choice. If a single organization and co-locational team members are solely responsible for the project, Agile is more effective.