1) The PMBOK Guide 4th edition made several changes to clarify concepts and consolidate processes. It removed 2 processes, added 2 new processes, and combined 4 processes into 2.
2) Key changes include clearer distinctions between project documents, more information on portfolio/program/project differences, and expanding the interpersonal skills section.
3) In the Initiating process group, it removed the Preliminary Project Scope Statement and added Identify Stakeholders. In Planning, it combined the 2 procurement processes and updated several process names to verb-noun format.