Physically they're the same, but the fact that they're in different locations enables them to pick up different signals, because the signals propagate to the atmosphere, and the ones that come from the west are stronger in the west than they are in the east. Also, if more than one station picks them up, which we hope they would, then it gives us the ability to direction-find them as well and find exactly where they came from: I know in which direction from me they came from, and you know in which direction from you they came from, and it's where they cross.
On February 18th, 2015. See this statement in context.