The Hawley retainer was named after its inventor and is the kind of retainers most people receive. It has a wire that runs across the front of the teeth which is held in place by an acrylic arch that sits on the roof of the mouth. The acrylic arch is often made of clear plastic and can have designs on it. The advantage of this retainer is that the metal wires can be adjusted to finish moving teeth as needed. It is also more durable than other retainers.
The Essix retainer, also known as a vacuum-formed retainer, is a transparent retainer that fits over the entire arch of the teeth. They are less expensive and less conspicuous than Hawley retainers but are prone to breakage, especially with patients with Bruxism.
A bonded retainer typically consists of a passive wire bonded to the tongue-side of the incisors. It is not removable and is often prescribed when there is a high risk for reversals in the positions of the teeth.