I just became interested in Tesla Coils a little while ago. I've seen pictures at pupman-dot-com, and other websites. I also saw a picture of a Tesla Coil in Edmund Scientific. In Edmund Scientific, it looks like an upside-down ice cream cone of coiled wire. At pupman-dot-com, they look almost identical to a Van de Graf Generator. What is the difference between the two, and how are they used differently? Thanks, Jamie.