Difference between agile and waterfall approaches to project management 

There are four principles which are typically used to highlight the difference between agile and waterfall (or more traditional) approaches to project management:

1. Customer collaboration over contract negotiation;
2. Individuals and interaction over process and tools;
3. Responding to change over following a structured plan;
4. Prototyping/working solutions over comprehensive documentation.

Chaos Manifesto Output

Source: Directing Agile Change

Traditional approaches

Traditional 'waterfall’ approaches will tend to treat scope as the driver and calculate the consequential time and cost; whereas ‘agile’ commits set resources over limited periods to deliver products that are developed over successive cycles.

Agile and waterfall approaches to project management exist on a continuum of techniques that should be adopted as appropriate to the goals of the project and the organisational culture of the delivery environment.

Overall, agile and waterfall approaches to project management both bring strengths and weaknesses to project delivery, and professionals should adopt a ‘golf-bag’ approach to selecting the right techniques that best suit the project, the project environment and the contracting parties with an emphasis on the behaviours, leadership and governance, rather than methods, that create the best opportunities for successful project delivery.

Pros and cons from the practical adoption of agile methodologies:

Source: The Practical Adoption of Agile Methodologies