This varies significantly between faculties. It depends very much on the nature of the discipline and the method of teaching, for example, faculties that require students to undertake laboratory work, studio work, practicum, field work, etc., have more contact hours than other faculties that require their students undertake more independent research.
Some faculties also have a portion of their teaching delivered on-line - this may be in addition to face-to-face classes or instead of face-to-face classes. Although in some instances you may not be required to be present physically to undertake these courses, you will still be expected to keep up-to-date. Do not succumb to the temptation of 'mañana' (tomorrow) - only to find that 'tomorrow' never comes! Irrespective of whether the majority of time is spent in class or on independent study outside class, the number of hours students need to commit to their studies will be the same for all courses.