Brats and metts are Cincinnati shorthand terms for common German sausages originally called "bratwurst" and "mettwurst".
Mettwurst is a type of soft, spreadable Rohwurst (raw wurst) which is a German sausage that is made from pork, and cured and smoked. It is jammed in casing but squeezed out of it, hence spreadable! In some regions, it is cured for longer time to resemble a salami.
Bratwurst is a unique wurst which is made of pork, beef, and veil. It is usually cooked in broth and beer. It is one of the most common and popular sausages of all.
Metts and Brats come in a number of varieties, and have numerous ways of preparation.
The spreadable Mettwurst needs no cooking as it has a soft texture, and hence can be eaten raw as well. The firm type can be baked, grilled, or stewed.
Bratwurst needs to be cooked before eating, though it is also available precooked in some markets. It is usually grilled, poached, stewed, or fried in a cooking pan.
Find out more about the major differences between the two at Buzzle.
Tip! Learn How to Properly Cook a Sausage from Chowhound.