The current (and currently called, in PF) "chicken dragon" has appearently two features the first traditional dragon doesn't have:
1. it can move the neck to look at one side and another
2. its wings seem to be more proper to give an impression it can fly
Personally, I find the old model of dragon better designed. And he's very funny, too.
They also say that the "chicken dragon" isn't of as good quality as the old model. I can say that this old dragon I've got is excellent quality material.
Gus
("chicken dragon" attached)