Analog vs digital
From The 07K Wiki
Analog signal
Analog signals varies in amplitude, they can be of different voltage level.
The signal can be interpreted either by the voltage level itself or by the frequency. For example, a sensor could output 0v-5v (this could be 0-100%) or a sensor could use the frequency to evaluate when an object accelerate (speed sensor for example).
Digital signal
Digital signals have two possible amplitudes. (two states : 1 or 0, On or Off)
Sensors can transfer data (signal) by varying the period (frequency). On digital communication, the frequency will be the same for each peer, they will listen to the 0 and the 1 for bytes that then get converted in messages / information.