How do u tell the difference between Country music, Western music, and Folk music?

I realize that country muziek is ascendant now, but there is still a distinction between country and western music, and it seems to me that there's a great deal of overlap with certain kinds of folk music, such as bluegrass and many traditional folk ballads. What aspects of the muziek do u point to in order to identify a gegeven piece as one of the other? It's always been hazy to me.