Difference between Waterfall Model and RAD Model

Differences Software & Coding Software Testing Testing Tools

The most basic difference between the waterfall model and the RAD model is that the waterfall model is a linearly-sequential life cycle model of software development in which software testing is done after the completion of all coding phases. On the other hand, RAD (Rapid Application Development) is an incremental model of software development. Read through this article to find out more about the waterfall model and the RAD model and how they are different from each other.

What is Waterfall Model?

Waterfall Model is the classical model of software development where each phase of software development is completed in a linear fashion. Once one phase is over, the next phase starts and in the end, the software development is marked completed. The waterfall model is also known as the classical model or the traditional model. This model cannot be used to handle large projects.

In case of waterfall model, the changes can be made in the project only at the beginning, and it is not compatible with the change in client requirements. Thus, the waterfall model is not flexible to changes. The waterfall model involves high amount of risk.

Waterfall model works for smaller projects and has only one single cycle of development. Following are the phases −

Requirement Analysis → Designing → Implementation → Testing → Deployment → Maintenance

What is RAD Model?

RAD Model or Rapid Application Development Model is also known as the incremental model of software development. It allows changes in any stage which was very costly in case of waterfall model. It has multiple cycles and each cycle delivers a version of a software and after each cycle, new features are added and software is enhanced.

The RAD model of software development does not require planning in the early stages of development. The primary goal of the RAD model is the rapid development of the application. The RAD model needs a small sized team for development. Also, any changes can be accommodated in the RAD model at any stage. Thus, it is a flexible model to changes as compared to the waterfall model. There is a low amount of risk involved in case of the RAD model.

Difference between Waterfall Model and RAD Model

The following table highlights some of the important differences between the Waterfall Model and the RAD Model −

Factor	Waterfall Model	RAD Model
Name	Waterfall model is also called as the Classical or Traditional Model.	RAD Model, Rapid Development Model, is also known as the Iterative Model.
Risk	Waterfall model is a high risk model for software development.	RAD model is a low risk model for software development.
Aim	The aim of waterfall model is to develop software of high assurance.	The aim of RAD model is to develop software rapidly.
Waiting time	In waterfall model, the waiting time for running the application is long.	In RAD model, the waiting time for running software is less.
Team Size	Waterfall model requires large team to start software development.	In RAD model, team size can be increased or decreased as the development progresses.
Changes	Any changes to be done should in the earlier phases of development otherwise, it is very costly to fix.	Changes can be done in any phase.
Product Delivery	Water fall model delivers product in the end of the software development cycle.	RAD model gives earlier deliveries and seeks feedback to update the software as needed.
Waiting Time	A running or ready software is available at the end stage of development.	A running or ready software is available as soon as first iteration is complete.
Customer control	In waterfall model, the customer control over the administration is less.	In RAD model, the customer control over the administration is relatively more.

Conclusion

The most significant difference between the waterfall model and the RAD model is that the waterfall model aims for high assurance of the application, whereas the RAD model aims for rapid development of the application.