Music 1 - Much easier. Scales shit. Designed for people who have just started learning an instrument with no understanding of music theory and who want to get into music. More practical to the real world. More relevant to music in the industry.
Music 2 - Much harder. Designed for people who have been playing for several years with a solid understanding of music theory and want to deepen their knowledge about specifically baroque/classical/romantic music and one area of your choosing. More theoretical. More relevant to music in academia.