ITIL V2 - V3 Differences??

What are the differences between ITIL V2 and ITIL V3?
What has changed?

Amongst the key changes you’ll see in ITIL V3 is a wholesale shift towards a service-driven lifecycle approach and guidance which aims to be more prescriptive.
Where ITIL V2 outlined what should be done to improve processes, ITIL V3 explains clearly how you should go about doing it.
Another key ITIL V3 addition is demonstrating return on investment to the business. This was one of the most frequent requests from the industry consultations, carried out as part of the version three project.

Structural Changes:

ITIL V3 includes some significant structural changes. The library now consists of five volumes, these are:

Service Strategy
Service Design
Service Transition
Service Operation
Continual Service Improvement

The foundation level exam syllabus has been expanded to include content from all five volumes. The new library also includes greater detail on the key roles, and outlines the responsibilities attached to each, along with clear focus on the importance of communication throughout the lifecycle. Greater focus on the use of process models and the identification of the constituent parts is all new to version three. Finally Continual Service Improvement or CSI, explains the use of process improvement models and identifies metrics to support improvements.