It seems like if a vertex is unselected, it is purple. However, if a face is selected it is purple. Is this right? Can someone explain this to me?
Yeah, that’s right. Nothing really to explain. It just makes it easier to see what faces/verts you have selected.
its just the interface. if you want to change it, go to user preferences, change it’s color, go back to your 3d veiw, hit ctrl-u, and then whatever color you made it will be defaulted.