How did Chinese students’ roles differ in the Great Proletarian Cultural Revolution of 1966-1976

How did Chinese students’ roles differ in the Great Proletarian Cultural Revolution of 1966-1976 and the 1989 pro-democracy protests in Tiananmen Square? How would you compare their motivations, ideologies, and results? Why do you think they acted as they did? What, if anything, do you think they had in common with Western students who led protest movements in the 1960s?