I think eSATA, has faster transfer speeds, than Firewire and USB....but Firewire and USB, allows for more length in their cables to transfer, than eSATA cables. Firewire and USB also allow for more than one device per channel, to be linked or daisy chained, while I think eSATA allows one.
To the best of my knowledge, an artifact is a loss of data or a defect, visible in an image or video. With gaming, it is usually seen, when the graphic card is overheating, or if it has been overclocked too far.