What are the names of different ways to fit video when the aspect ratios do not match?
Letter box if you have bars on the top and bottom.  
Pillar box if you have them on the sides.  
Stretch (or possibly anamorphic, depending on what the intended playback aspect ratio is)   if you are full screening it by stretching it out to fill the space.  
Cropped if you are making it full screen by cutting off the edges.