Sorry, didn't notice you respond.
http://archive.foolz.us/co/thread/58635220/#58644717It seems like the guy was cutouts, transparencies, and alpha masked images.
I think "Cutout" would be screencaps from the show who have all the background stuff removed, leaving just the character. "Vectors" are those fuckhuge cutouts we sometimes see. Transparent_Background could apply to both cutouts of screencaps and fanart with transparent backgrounds.
They're more like irregular generals.