Welcome to the group Anders, we're glad you're enjoying PCO.
As JMass and Mobius have said, all units in platoon must use the same primary order (Rush, Advance, Engage, Defend...etc). But some of these primary orders have sub-orders. This sub order can be different withine the units of a platoon. This allows you to set up over-watch type moves, where two elements of a platoon might Have Engage --> Move order while a third element of the same platoon has an Engage --> Hold order. Also, during the reaction phase, there are other actions that can be assigned to individual units within a Platoon.
In the Maps, Models and Mods sticky thread there are several mods that players users have created.