Despite some geographical differences like size, a mountain lion, puma, cougar, and panther are all the same cat.
A Cougar, scientifically named Puma concolor, also goes by names like red tiger, mountain screamer, painter, and catamount. In fact, it has so many names it actually holds one of the Guinness World Records for having the most names due to having more names than almost any other mammal (40 in English alone).
These names generally originate from the many different places where the Cougar is found. Speaking of which, although all of these names are names for the same type of cat, there are slight differences in size relating to the name and location of the cat due to regional factors like diet and climate.