Spusa,
The helicopters mentioned are easy to learn to fly, as is each helicopter is easy to learn to fly after your initial helicopter training. The big difference is the role of the helicopter, and each person's ability to adapt to those roles. The Apache, for example, can be overwhelming, in not that it is difficult to fly, but because of the multitude of systems involved. Not to mention the knowledge the pilot must have of things outside the cockpit. Like tactics, vehicle and threat recognition, enemy weapon systems, etc. The same for the sea king, in a SAR role for example, there is a lot going on that must be managed by the pilot, all the while safely flying the helicopter.