what do the difference between using GPU or CPU for rendering? I wanted to speed up my rendering time, and I found that using GPU speed up a lot. But I don't have a very fast GPU (NVIDIA GeForce 320M 256 MB), so I want to know what do the difference between using GPU or CPU, so I would compare my CPU (2,66 GHz Intel Core 2 Duo) with my GPU (NVIDIA GeForce 320M 256 MB).
Gpu's have many cores (yours may have 72 cores) but they run at lower speed (frequency) .Gpu cores can understand simpier instructions that a cpu core can understand.Cpu has much less cores than gpu cores but they run at higher frequency and they understand complex set of instructions.These are some key differences.