American Short Haired - Description: short, sleek hair.
Abyssinian - Description: short, rough coat with cowlicked rosettes all over.
Peruvian - Description: long, sleek hair that grows over face. When hair is left long, the front and rear ends are indistinguishable. Hair must be trimmed and brushed frequently. If left to grow, it can get to lengths up up to 20 inches long!
Silkie or Sheltie - Description: long hair that flows back, never over face as in the Peruvian.
Rex - Description: wooly, dense, short hair that stands on end.
Teddy - Description: dense, fuzzy coat with hairs that stand up. Longer hair than a Rex, especially coating their bellies.
Texel - Description: long, curly hair that flows back, never over the face. Curles cover entire body and are tightly wound.
For more information: http://en.wikipedia.org/wiki/Guinea_pig_breed