The activities in project planning should differ because you have to work out how to achieve your goals relating to your project. A high percentage of the work while planning refers to building a strategy to get everything done and putting the structure in place to make it happen. By structure, we mean the processes and governance to keep everything running smoothly and bring effectiveness. These are things like the change management process, the budgeting process, what quality measures are important, etc. Remember, that planning as the approach to the work has the key goal: the better impact and performance.