The process is: when you are outside Canada you have to apply for temporary resident visa. When you are already in Canada and want to extend your stay as a Visitor (not a student or a worker) you must apply with the other forms. You r still temporary resident. The difference is the only that you continue to be visitor=tourist. Or u can change your status and become a student, but still you are temporary resident. The term "visitor" is used to differentiate temporary residents - students, workers and visitors and find that package of forms which is needed to file for every particular case.