I think the best thing to do first when
learning about varieties/errors etc. (or just plain coin collecting period for that matter) is to watch and or read
about the whole process involved with minting coins.
From start to finish. Get to know the correct terms used also.
The two main areas on a coin are the fields and the devices.
The devices I believe are what you are referring to. They are the "raised" areas. On
DDO's/ddr's the doubling is actually on the die.
Part of it's design. Not intended to be in the first place but an actual mistake that was made by the engraver. It could also have been
as in many cases on the master hub and or hub/hub's from which working dies are created from. The doubling can be in different positions. They could be north,south,east or west or in between.
Or a mix of them all on the different devices. Take a look below at the classic 1955
DDO. Notice how on all three device areas (date,motto and liberty) the postion of the doubling is different in all of these areas. This particular
DDO was from the master hub. Then got transferred to the working die. As far as how "high" the devices
are raised has to do with the actual engraving of the die/hub in the first place then the pressure used during the striking process of the coin. They may vary from coin to coin some. As far as "knowing it all"
i use this analogy. When I was 25 years old I knew everything there was to know about Women. 30 plus years later I now know nothing.

Let's just say this. You learn something new every day and will continue to do so. I know, I just forgot.

