See the rest here:Don't confuse sphagnum moss with sphagnum peat moss. Sphagnum moss and sphagnum peat moss are not the same product. Sphagnum moss is used in the floral industry to line wire baskets and make wreaths. It is the LIVING moss that grows on top of a sphagnum bog. Sphagnum peat moss is used as a soil conditioner by gardeners. It is the dead material that accumulates in the lower levels of a sphagnum bog. Harvesters of the horticultural peat moss remove the top few inches of the live sphagnum moss before harvesting the peat from the lower levels of the bog.
http://www.ext.vt.edu/departments/envir ... agnum.html
More information here:
So, "peat moss" could be the bog soil while "peat sphangum moss" could be the actual moss plant. I haven't run into "peat bricks", but I have run into bricks of the actual moss. Most things just labeled "sphangum moss" are the actual moss.
Hope that helps,