By definition, an analog signal encodes an “infinite” amount of information in whatever value it is taking on at the time point in question, while a digital signal encodes information in discrete states. For binary that is typically two states, but sometimes you can divide things finer, like multilevel flash cells or PAM4 signaling.

Digital the values “round-to-nearest”, so if supply is 1 V, then 0.6 V, 0.9 V, and 1 V all mean logical 1. Whereas for analog those different values mean different things.

Also, for digital you want to push the signals to the extremes so they are easier to read, while for analog that would be destroying information, you want to preserve the value.

(In practice there are fundamental limits to how much useful information you get out of analog signals due to noise.)