When evaluating on how a bit will work in a horse's mouth it is important to look at how the whole bit will function as a whole and not just a singular part. When comparing these two bits, they both have a very similar mouthpiece but due to the shanks and the mechanics they will have very different reactions for the horse.
The Figure Eight bridle gets its name from the noseband. It starts up by the cheek, crosses up and over the nose then down around and in front of the bit. It can also be called a Grackle, Mexican or simply a Crossed noseband. These types of nosebands are used to help prevent the horse from crossing their jaw. The center of this noseband can either be leather lined, or a sheepskin or fleece padding depending on the style.