The things which are different about these from the basic terrain dice are that they include 'no 24s allowed' and 'no 30s allowed' sides. Also, more than one type of dice can be restricted or enhanced on turn, so there is more variety per round.
Here is a chart with all the dice and their sides, if you want to make your own.
4x2, No 4, 12x 2, No 12, blank, blank
10x2, No 10, 20x2, No 20, blank, blank
6x2, No 6, 8x2, No 8, blank, blank
More about Armies of the Dead.