Metal brackets are the ones that are most frequently used. They appear as small metal buttons that are glued to the front of each tooth. These tend to be less expensive than other types of brackets. Additionally, they can be made colorful with ligature rubber bands that come in a wide range of colors.
A major drawback of these braces is there color which makes its use very limited in cases of adult orthodontics.
Ceramic brackets are made of composite materials. They are very strong and generally do not stain. Adults like to choose ceramic because they "blend in" with the teeth and are less noticeable than metal. The ligatures (tiny rubber bands) that hold the arch wire on to the ceramic brackets are often white or clear. This looks great at first, but the ligatures can stain. Unless you eat a lot of curry, smoke, or drink a lot of black coffee, this generally isn't a problem. Note that the ligatures are changed each time you get an adjustment - usually, monthly. It's only the ligatures that stain, not the brackets themselves!