1) Wavelength is the distance between repeating units of a propagating wave of a given frequency. Designated by the Greek letter lambda (λ).
2) Frequency is the measurement of the number of occurrences of a repeated event per unit of time. It is also defined as the rate of change of phase of a sinusoidal waveform. (To calculate the frequency of the event, the number of occurrences of the event within a fixed time interval are counted, and then divided by the length of the time interval.)