How to select the output of water level sensor?

It's important to select the output of water level sensor. But I don't know the difference between digital water level sensor and analog water level sensor, does anybody can tell me about this? thanks in advance.
Usually, a digital output refers to some kind of "encoded" output which has to be "interpreted" or "read" or "deciphered" by some device in order to produce an output which can be expressed in some terms like voltage or current or engineering units on some display. Examples of digital outputs might be Profibus, or Fieldbus or MODBUS or CAN or HART or some similar communication method/protocol.

An analog output is one that is already in either a voltage or current value that is proportional to the parameter being measured. In your case, water level sensors, that would be volts-per-mm or milli-amps per cm, or something like that--some analog value (which can easily be measured using a voltmeter (analog or digital) and the value of which is proportional to the depth (heighth) of water in some vessel.

Your welcome.