Understanding Lampshade Lingo and how the parts fit together to make a Lamp
Regular spider sits on a harp on top of a lamp.  
The spider can be at the top or have a drop.
   
Euro spider is a spider with a euro washer or a 205 washer.  These usually sit below the bulb and have a drop.
   
Bridge fitter is a fitter that screws onto the lamp.  
Usually a bridge lamp.
   
Bulb/chandelier clip is a clip that is separate or attached to the shade.
It can come in either a bulb clip or a chandelier clip depending on the size of the light bulb.
   
  Finial is the thing that holds the lampshade onto the lamp.    
Harp is a piece of wire that holds the shade onto the lamp. It can come in a variety of sizes.