Whats the difference?

[GT-7]

Well, ive found this pritty good pc for its price from a finish store. But theres one thing i dont know. The pc has 256MB of video memory, but then there also reads that theres 1023MB of shared video memory.

So, whats the difference between video memory and shared video memory?  

[Rok]

A shared video memory is taken from the RAM i think