There is no difference between the cougar and the mountain lion as both are the same cat called the Puma concolor. The Puma concolor has been called many names in addition to mountain lion and cougar, such as panther and puma.
The reason that the Puma concolor has so many names is that the many people who have encountered it through the years gave them different names. First, Spanish adventurers found the animal and called it a "leon," which is a lion and "gato monte," or "cat of the mountain." Then the Incas called the animal a "puma" in Incan language, which was then followed by "cougar" from the South American Indian word "cuguacuarana." The term "panther" was a term for all cats that had a coat of one color, so the Puma concolor was given that name as well.
The cougar can be found in prairies, swamps, forests and deserts throughout the western parts of Canada and the United States as well as southern South America. The U.S. cougar population includes a small group in Florida. This particular cat has black ears, black patches around its mouth, a pink reddish nose, pink insides of the ears and an almond tan coat. Some cats have additional white patches around the eyes.