Yes, the chambon only has one setting and you can only lunge in it, but the de Gogue has two settings and you can lunge and ride in it.
It's a bit complicated to explain, you'll have to see if you can find some pics on the internet to help you understand how they work!
They do work on largely the same principle, but the de Gogue is a bit more versatile as you can ride in it. I personally find my horse lunges better in the de Gogue than the Chambon, but it really depends on the horse.
I'm about to purchase a chambon - partly after reading the sustainable dressage website!! I am worried that my horse might feel restricted and freak out a bit when he first has it on. He doesn't usually freak out at anything, but he has a rather high head carriage. Can you vary the length of it so they can get used to it more gradually?
The de gogue will help bring the head on to the vertical. I have started lunging in my de gogue after approx 4 months lunging in the chambon. They do complement each other.
I have had no problem with restriction at all with either, however my horse totally freaked out in side reins that were very loose yet didn't mind a tightish de gogue at all.
The chambon is by far (imo anyway) the most useful thing to use to build muscle.