The purpose of the 200k is to teach you the basics of how it all works. How to follow a route. How to get your card validated at controls. How to ride within time limits.
The purpose of the 300k is to teach you how to take care of yourself on a long ride. How to stay on top of your food and water consumption. How to keep going when you get tired without hurting yourself.
The purpose of the 400K is to teach you how to ride at night. How to equip your bike with lights that meet your needs. How to stay safe in the dark.