A true 0V is where would have a material where you would have equal numbers of protons and electrons. The earth ground may not necessarely have, at a specific point, for a specific moment, exactly this condition, but is very close.
When you see things like Analog GND, Digital GND and other GND, this is marely to distinguish between different GND path, which should be electrically treated independently. For example, in a digital circuit, you can see analog and digital GND. The digital circuitry will create a lot of noise, and the current flowing through the GND traces or plane will be very noisy. As a result, any chips connected to that GND line will pick-up the noise. The farther you get on the GND lines from the main entry capacitor, the greatted the noise sum will be. On digital chips, this usually doesn't cause too much problems, but if you also have analog circuits, for example an analog to digital chip, where you would sample voltage beween 0 and 4.095V, with 4096 different steps (12 bit ADC), then the noise on GND line will definitely affect the readings.
This is why you must use a GND signal that is clean. It is still 0V refference, but must be a different GND than the noisy digital GND. So, analog GND is a GND signal, that is independent from Digital GND, and is connected to the same point as Digital GND *only* at the input capactor, where the voltage is regulated. You mau also see Analog VCC (or AVCC), in a similar way as for GND. It is not rare to also see choke coils or little ferite beads to make sure there's no feedback from the digital circuitry.
When a circuit reffer to earth GND, it often reffer to the chassis GND (the metal box and supporting frame), where the chassis is also connected to the power outlet GND line. This is more common in power-supplies, and in home appliances.
Though, exceptions exists, and older circuits schematics sometimes mixed the GND symbols.