Rodney

AM and FM are just describing the type of modulation the RF is encoded with. AM is amplitude modulation where the instantaneous strength or magnitude of the signal is modulated or varied from zero to maximum for that transmitter. FM puts out a constant strength or magnitude signal and the encoding is done by varying the frequency a small amount about the center frequency. Either type works well for the way RCers use them and each has some advantages over the other. For our puposes, FM usually provides more resistance to minor interferance. As to tc3mafias question, frequency has very little to do with range over the span you are asking about. Receiver sensitivity (usually stated in DB/Meter) is the prime factor for range, the smaller number is better. This is assuming the power output of the transmitter is the same for all the frequencies. Also selectivity is important but that is a number most manufactures don't publish and some of the less expensive units suffer in both respects.