Frequency modulation (FM) and amplitude modulation (AM) are both techniques used in communications. FM encodes information in the frequency of the carrier wave while maintaining a constant amplitude, making it more resistant to noise and interference. This results in higher sound quality, which is why FM is often used in broadcasting. In contrast, AM varies the amplitude of the carrier wave to transmit data, making it more susceptible to distortion and noise, thus generally resulting in lower audio fidelity.