11 Aug 2020

Agile vs Waterfall: What’s the Difference?

Agile vs Waterfall: What’s the Difference?

In the ever-expanding world of project management methodologies two of the heaviest hitters are Agile and Waterfall.

Both have been around for some time, with Waterfall appearing some 50 years ago and Agile, a relative newcomer, at about 20 years old. Both emerged as tools for principally managing software development but are now widely applied across very different types of projects.


To put it simply Waterfall is essentially making a good plan and sticking to it, while Agile utilises a more flexible, iterative approach. Waterfall is more sequential and pre-defined, while Agile is more adaptable as a project progresses.

Agile is more a set of principles than one methodology. Its principles are applied in other more specific methodologies such as Scrum, eXtreme Programming, Kanban, and Scrumban. It is a practice based on continuous iterations of development and testing where such activities can run concurrently. Agile projects are characterised by a series of tasks that are conceived, executed and adapted as the situation demands, rather than a pre-planned process.

Want to learn more? Check out our guide, Agile: Everything You Need to Know.

Waterfall, on the other hand, is much more linear, focusing on up front planning with requirements fully defined before a project commences. Like its name suggests, work cascades, much like a waterfall, through different project phases. Each phase needs to be completed before the next one can begin.


Agile pros:

  • Agile’s flexibility avoids rigidity. Stakeholders and team members have opportunities to observe and test throughout the project which allows for adjustments and changes to be made as things move forward. This greater “user focus” means that on delivery it’s likely the outcome will be more in line with expectations - even if they have evolved along the way.

  • Agile encourages teamwork, collaboration, self-organisation and accountability. This helps with overall motivation and commitment to a project’s outcomes and goals.

Agile cons:

  • Because of its flexibility and ability to adapt, an Agile project can run the risk of losing direction or falling behind schedule. Constantly iterating and re-aligning a project can easily stretch budgets and timelines.

  • Adherence to Agile principles mean that team members are almost completely dedicated to the project which can be challenging from a resource or continuity point of view. While this kind of focus can lead to faster outcomes it may not lead to better ones if the project feels uncontained or has lost focus.

Waterfall pros:

  • Waterfall is particularly efficient for well-defined projects. Project stakeholders agree upfront on what will be delivered, which makes planning and design much easier. Progress is more easily tracked as the full scope of the project is known from the beginning.

  • Unlike Agile, this more linear approach often means that team members only need to be available for their specific project phases and can thus continue to focus in other areas. Equally a project’s customers may only need to be involved heavily in the early initial scoping phase and then at delivery.

Waterfall cons:

  • On the downside, Waterfall requires comprehensive requirements up front which can sometimes be challenging for more complex or longer-term projects.

  • Its sequential nature and reliance on pre-planning means there is a certain rigidity built into the project that makes mid-project pivots or directional shifts difficult to deploy without re-engineering all those pre-made plans.  


As always, choosing which methodology (Agile or Waterfall) is right for your project is entirely dependent on the nature of the project you have in mind and the culture and type of organisation you work for. Of course, the reality might be that a hybrid Agile Waterfall approach makes the most sense for your project but there are some general rules of thumb.

Agile makes sense where a project is based on incremental progress, complex deliverables or consists of multiple, not always sequential timelines. Projects that require cohesive and collaborative but cross-functional teams to deliver will need to take an Agile approach.

If processes or roles are unclear it makes room for figuring it out as the project goes along. It also allows for involving the project client at any stage along the way. Products that are developed in stages, updates or versions are particularly suited to Agile.

Waterfall is usually more suited to less complex projects or those that have well defined requirements, processes and roles for team members. Single delivery timeframes with lots of detail and an expectation that very little is likely to change along the way are ideal.

Waterfall also works well when the client is not required to be heavily involved beyond the initial brief and final delivery. From a management point of view, Waterfall can often make sense for fixed-price or contract dependent projects in order to lessen the risk of budget or delivery over-runs.


So take the time to consider the best way forward before you get underway. Know your project goals and determine the variables, dependencies and activities that are crucial for your project.

Identify the metrics and success factors that are most critical and review each methodology for the best match. Engage your team in the decision-making process and assess their familiarity and experience with different methodologies. Finally, whatever choice you make, stick to it! Changing horse mid-race rarely ends well.


Did you know here at the Australian Institute of Project Management, you can gain recognition for a completed certification which includes some Agile credentials? Find out how you can be automatically granted the AIPM Certified Practising Project Practitioner (CPPP) level of RegPM.