Expert adds more terrorists and demands a high level of expertise and success. The Planning Phase is a jaw-dropper, but it's pretty easy to get a handle on. The first four missions have default mission plans for your convenience. It's very helpful to see a plan already laid out. By the fifth mission, you should be ready to create your own.
Movement is defined by waypoints.
For example, the plan at right has four teams entering the Embassy via different locked doors. These doors need to be either picked or blown. For the sake of surprise and confusion, breaching charges will be placed. Each team is allowed to get into position and place its charge. I can't overemphasize the importance of getting the plan set up correctly.