Don`t know about the internel version, but the external version really had a difference. Exactly as suggested, the scanmagic is a mere scandoubler while the flickermagic compensates the flicker of interlaced modes too.
The only difference you could see without looking into the logicchips itself would be soem RAM-chips that hold the buffered image.
Here is an old ad, that says I`m right
http://home.joice.net/j100513/scans/temp/ad.jpg
