A diploma course will teach the different students differently. An instrumentalist will be taught how to play his instrument in various performances. He will be taught to perform solo, in a choir or in an orchestra. A vocalist will be taught languages to understand the songs, along with his music lessons. One who intends to become a composer will be given lessons on techniques.
A diploma course is more job-oriented. It prepares the musician for the job he wants to enter. Either as a musician, a music teacher or a conductor. It will allow student to experiment with different styles and perfect his music.