PRINCE2 is a practical, process-based methodology which provides detailed, step-by-step guidance on delivering a successful project with transparent processes, steps, and templates.

ITIL Certs comes from the same stable as PRINCE2 Certs so, unsurprisingly, is also process-based. It aims to give you the ability to improve how IT is delivered and managed within an organization. Using ITIL, you can continually improve efficiency, effectiveness, quality and cost management. ITIL has traditionally been used for IT, but increasingly organizations are finding it can be utilized in a variety of settings for a variety of purposes. CERN - the location of the Large Hadron Collider - is using ITIL for non-IT situations as reported by Computer Weekly.
ITIL is again a set of highly structured Processes for IT Service Management. It is imperative to understand what is the difference between Project Management and Service Management. Will try to put it in very simple terms using an example.
Business requires a CRM application, and they request the IT-S/w development team. This team decides to build/develop this CRM application, and they take this activity as a Project. When this project is over successfully, it will deliver a CRM Product or a CRM Service but via a CRM application. Right from the starting till the end of the Project, the project team/project manager are managing the six aspects Scope, Timeline, Cost, Risks, Benefits, Quality.