What is the difference between process groups and knowledge areas?

The process groups divide up the processes by function. The knowledge areas divide the same processes up by subject matter. Think of the process groups as being about the actions you take on your project, and the knowledge areas as the things you P need to understand. In other Words, the knowledge areas are more about helping you understand the PMBOK® Guide material than about running your project. But that doesn't mean that every knowledge area has a process in every process group! For example, the Initiating process group only has two processes, and they both show up in the Integration Management knowledge area. The Risk Management knowledge area only has Planning and Monitoring & Controlling processes. So the process groups and the knowledge areas are two different ways to think about all of the processes, but they don't really overlap