The difference between frequency and amplitude is that frequency is a measurement of cycles per second, and amplitude is a measurement of how large a wave is. Amplitude represents the wave's energy.
Waves are defined as energy transferred from one place to another. The way in which the energy travels is called the medium. These waves can be in the form vibrations through light or matter, such as solid, liquid, or gas (e.g. sound waves or earthquakes). The most important terms in relation to these waves are wavelength, frequency and amplitude.
Wavelength is directly related to frequency because it describes the displacement between the waves, whereas frequency describes how many waves pass within a second. Larger wavelengths are associated with lower frequencies, and smaller wavelengths are associated with higher frequencies.
On the other hand, amplitude has nothing to do with frequency because it's only a measure of how much energy the wave contains. Large waves contain more energy than small waves. For example, a sound wave with a high amplitude is perceived as loud.
Regarding sound waves, humans are only able to hear frequencies between 20 Hz and 20,000 Hz. Since humans are only able to perceive these frequencies, devices such as radios and wireless routers operate on much higher radio frequencies, such as 100 MHz and 2.4 GHz.