In my previous blog “A quick overview of Scrum and Extreme Programming for the beginners“, I gave a brief introduction on Scrum and Extreme Programming.
If we talk about similarities and differences between Scrum and XP, in some ways they are same and yet in some ways they are different.
Scrum and Extreme programming, both are referred as “Agile Methodologies”, used in software development to improve software quality and increase productivity. They are so aligned with each other that it is hard to distinguish whether you are using Scrum or XP.
In this blog, let’s go through the actual differences between Scrum and XP.
1) Both Scrum and Extreme programming works in a time-boxed iteration to finish a set of tasks. Scrum team takes 2-4 weeks to complete this iteration, which is also called Sprint. In most cases, it is fixed for the duration of a given project. The purpose of a Sprint in Scrum is to deliver a product increment, which means a coherent release of some features.
On the other hand, XP has a shorter iteration of 1-2 weeks. This gives benefit to the team when requirements change rapidly.
2) In the scrum, product backlog items for the sprint are finalized at the time of planning, beginning of the sprint. Once a sprint has started, nothing else is allowed to be added. All planned items remain unchanged through the end of the sprint. Whereas in extreme programming, the team are flexible and can swap items as long as development has not been started on them. The team can swap feature with a feature of equivalent size.
3) In the case of Scrum, the product owner sets the priority of product backlog items but it is up to the team to decide what will be implemented. The team has the flexibility to choose the items and implement them in the order of their priority.
In the case of Extreme Programming, items are implemented in a strict priority order. It is the customer, who decides the priority and team has to work on them in the order, specified by the customer.
4) Scrum doesn’t focus any engineering practices. It focuses on team, Scrum is more concerned about productivity. It has some well-defined roles: Product Owner, Scrum Master, and Scrum Team. It has some organized ceremonies such as Sprint planning meeting, daily scrum, sprint review, and sprint retrospective.
In the case of extreme programming, it comes with a set of engineering practices that it prescribes like Test-Driven Development, Refactoring, Pair Programming, Continuous Integration, simple design and so on.
These are the main differences between Scrum and XP. Both works in iterations and both are flexible enough to handle a volatile changing project. In my suggestion you can start with Scrum and adopt XP practices along the way.