Almost every project is embedded within a larger system, either as part of program management, multiple project management or simply alongside the line functions. Project managers therefore often have to see and understand the overall system so they can detect and master any disturbing factors. You should know who else is on board (stakeholder analysis) as well as which rules apply within the system.
Internal or external projects pose different challenges, particularly with regard to how they are steered, including communication with the clients (steering committees). Project managers often have good technical background knowledge but are less experienced in reflecting procedures of value-creation and adding value to business, as well as questioning how personal decisions were made and attempting new approaches and strategies.