The piezoelectric buzzer uses piezoelectric materials. When subjected to external force causing the piezoelectric material to deform, the piezoelectric material will generate electric charge. Similarly, when powered on, the piezoelectric material will also deform. 

The electromagnetic buzzer mainly utilizes the characteristic that an electrified conductor can generate a magnetic field. A fixed permanent magnet and an electrified conductor are used to create magnetic force that drives the membrane fixed on the coil. 

Due to the different working principles of the two types of buzzers, the piezoelectric type has a simple structure and is durable but has a monotonous tone and poor sound quality, which is suitable for use in alarm devices, etc. While the electromagnetic type has a better sound quality, so it is mostly used in voice, music, and other devices.