AM and FM are two famous means of sending information via the airwaves. AM stands for amplitude modulation, while FM stands for frequency modulation. Modulation is a means of modifying an aspect of the carrier frequency with respect to the information being transmitted. This, AM modifies the carrier frequency amplitude, while FM modifies the frequency. AM is older and easier to implement than FM. For AM, the receiver discovers the changes in the amplitude of the carrier frequency, and amplify or modify it to drive a speaker.
Though FM is more difficult to implement than AM, it offers a whole lot of substantial benefit than AM, and it is a technological development built over AM. The frequency modulation makes use of advanced logarithms to send two channels of information just at the same time. FM is ideal for music as it can transmit in stereo, though it does not have a long-range than like AM.