Depending on the situation lol. Also, i searched on newegg recently, there are only 10 types of 6800 GS.
6800 GS will come in AGP or PCI-E. People normally will refer to the PCI-E ones.
Of all the 6800 GS PCI-E, it will be different in brand names. Many companies makes the card.
Sometimes, the 6800 GS PCI-E might be 256MB or 512 Mb as well.