Standard rotors are 1 piece. May have many designs or patterns cut into them, but still one piece.
Floating rotors are 2 piece (more if you count the pins), inner and outer. They are attached by pins or rivets that are about the size of a nickel. The two pieces dissipate the heat better and won't warp as easily. If you go to ebay and type in Harley floating rotor then Harley rotor you will see pictures of both.
Look close, at first the difference is subtle.