It's not only cloth. When they got added in a patch there was a thread asking the same. They actually have metal as protection inside the helmet, therefore more armor than the coif.
A coif doesnt have a lot of protection anyway... a coif is more an addition to other helmets, but I wouldnt wish to fight someone and get hit to the head when just wearing a coif irl. Cant say about those other 2 helmets but if its true that they have metal in them, they do indeed give a bit more protection.
edit: I dont know if I am right, thats what Ive read. Cannot find the thread anymore though.