Peyotl is commonly known as Peyote. It is a small spineless cactus which produces psychoactive alkaloids (drugs that alter brain function) such as mescaline, and is a native plant to Mexico. It is used by Native Americans in certain ceremonies to produce feelings of transcendence and ecstasy, as well as a curative for various ailments. Aldous Huxley described his own experience with mescaline in The Doors of Perception.
Mescal (or Mezcal) is a colourless liquor produced from the maguey plant, which is native to Mexico. Despite the similar name, it does not contain mescaline.